• Structural Engineering and Mechanics
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• v.77 no.1
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• pp.103-114
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• 2021

Ultra high strength concrete (UHSC) originally proposed by Richards and Cheyrezy (1995) composed of cement, silica fume, quartz sand, quartz powder, steel fibers, superplasticizer etc. Later, other ingredients such as fly ash, GGBS, metakaoline, copper slag, fine aggregate of different sizes have been added to original UHSC. In the present investigation, the combined effect of coarse aggregate (6mm - 10mm) and steel fibers (0.50%, 1.0% and 1.5%) has been studied on UHSC mixes to evaluate mechanical and fracture properties. Compressive strength, split tensile strength and modulus of elasticity were determined for the three UHSC mixes. Size dependent fracture energy was evaluated by using RILEM work of fracture and size independent fracture energy was evaluated by using (i) RILEM work of fracture with tail correction to load - deflection plot (ii) boundary effect method. The constitutive relationship between the residual stress carrying capacity (σ) and the corresponding crack opening (w) has been constructed in an inverse manner based on the concept of a non-linear hinge from the load-crack mouth opening plots of notched three-point bend beams. It was found that (i) the size independent fracture energy obtained by using above two approaches yielded similar value and (ii) tensile stress increases with the increase of % of fibers. These two fracture properties will be very much useful for the analysis of cracked concrete structural components.

• Elastomers and Composites
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• v.59 no.1
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• pp.34-41
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• 2024

In this study, the effects of the type and content of silica on the mechanical and tear properties of chloroprene rubber (CR), which is mainly used as a jacket material for mining cables, were studied. The crosslinking density (ΔM) and reinforcing factor (α_f) defined using cure characteristics increased with increasing silica content, whereas the cure rate decreased. The hardness, tensile strength, and modulus of the CR compounds increased depending on the silica content and structural development. The reinforcing behavior of the silica-filled CR compounds according to the silica type and content showed the best fit with the Thomas equation of the predictive model. Tear strength was evaluated using two standard test methods, ASTM D470 and DIN VDE 0472-613, and the results were compared. The tear strength increased as the silica content increased, regardless of the test method, and the different tear strengths obtained by the two standard test methods showed a linear relationship with each other, indicating a high correlation.

• Journal of Distribution Science
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• v.14 no.8
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• pp.93-100
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• 2016

Purpose - This study examines lenders' reactions to M&A, based on the strength of the lender-borrower relationship and the lender's expectations of the potential benefits or risks of the deal. Research design, data, and methodology - This research addresses the lender's influence on the implementation stage of a large-scale strategic action such as M&A to understand the motivation and dynamics of lenders' responses and empirically examines how the lender-borrower relationship influences the focal firm's merger and acquisition (M&A) transactions, using data on 501 M&A deals in Japan from 1990 to 2010. Results - The presented analysis found that lenders that have a strong lender-borrower relationship, especially those showing a high debt equity ratio, support borrowers' M&A progress and the target firm's lenders resist the deal progressing and may raise the acquisition premium if their current power relative to borrowers is weak. Conclusions - Stakeholders including lenders do not favor strategies of focal firms that threaten their future benefits, while they also tend to estimate the potential benefits and losses by comparing their current circumstances with those of other stakeholders. The empirical results of the presented analysis help explain the mechanism of lenders' reactions and offer insights into the power of a closer and stronger lender-borrower relationship.

• Geotechnical Engineering
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• v.13 no.6
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• pp.71-94
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• 1997

It is important to evaluate rock strength in order to check stability of a rock slope or to design a structure built on rock. However, test methods used for the evaluation have some difficulties since rock samples provide various deviation of strength due to micro cracks in the samples and teat errors, Also, reliable data have not been accumulated for the rock strength in Korea. Therefore, simple teat methods that can be used easily for investication of rock strength in field or in laboratory are not provided sufficiently yet. This study is to investigate variation of the rock strength due to the degree of weathering and to evaluate the degree of weathering by types of rocks, by using data that have been obtained for several years. Therefore, it is possible to provide a relationship between several rock strength values by performing tests such as uniaxial compression teat, point load test, schmidt hammer teat, absorption ratio best and slaking durability tests. The equations of relationships that can be used to estimate rock strength by using simple test methods in field and in laboratory are proposed.

• Journal of Korean Society of Steel Construction
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• v.24 no.6
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• pp.711-723
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• 2012

Structural tests were performed to investigate the structural performance of concrete-filled steel tube column using different strength steels in their flange and web with high-strength steel HSA800 and mild steel SM490, respectively. The test parameters included the strength of column flange and infill concrete, and effect of concrete infill. Connection between different grade steels were welded using the electrode appropriate for mild steel and verified its performance. To evaluate the behavior of test specimens, eccentric loading tests were performed and the results were compared with the prediction by current design codes. Axial load and moment carrying capacity of test specimens increased with the yield strength of compression flange and weld fracture occurred after the specimen shows full strength. The prediction result for axial load-bending moment relationship and effective flexural stiffness gave good agreement with the test result.

• The Journal of Engineering Geology
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• v.30 no.1
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• pp.85-101
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• 2020

The estimation of strength parameters is very important for the stability analysis of rock slopes. Various methods for the determination of strength parameters were suggested by various researchers. The number of methods used for the estimation of strength parameters in the stability analysis of rock slopes were investigated based on literature reviews. The frequency of the method determining strength parameters were investigated with respect to failure types. The cohesion and friction angles of the rock and discontinuities are presented with RMR values. The cohesion shows wider range of values relative to those of friction angles according to current studies. Even though RMR does not show any correlation with cohesion values, RMR and the friction angle of the rock clearly shows a positive relationship. Proper methods should be utilized for the determination of strength parameters with consideration for failure types and be proved through literature reviews. The credibility of determining strength parameters is expected to improve if strength parameters data are accumulated from the back analysis performed for failed local rock slopes.

• Korean Institute of Interior Design Journal
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• v.24 no.2
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• pp.125-133
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• 2015

Gaze induction characteristics in space vary depending on characteristics of spatial components and display. This study analyzed dominant eye-fixation characteristics of three zones of department store space. Eye-fixation characteristics depending on spatial components and positional relationship can be defined as follows. First, [**.jpg] was used as an extension in the process of storing the image photographed during image data processing for analysis in pixels and due to compressed storage of image data, the image produced with a clear boundary was stored in neutral colors. To remove this problem, the image used in operation was re-processed in black and white and stored in the [**.bmp] format with large capability, at the same time. As the result, the effort caused by unnecessary colors in the program operation process was corrected. Second, the gaze ratio to space area can be indicated as a strength of each gaze zone and when analyzing the gaze strength of the three zones, the left store was a zone with a "little strong" gaze strength of "102.8", the middle space was a zone with an "extremely weak" gaze strength of "89.6" and the right store was a zone with an "extremely strong" gaze strength of "117.2". Third, the IV section had a strong strength of gaze on the middle space and the right store and the V section showed a markedly strong strength of gaze on the left and right stores. This tendency was the same as the VI section with the strongest gaze strength and the right store had a little strong gaze strength than the left store.

• Journal of the Korean Society of Physical Medicine
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• v.15 no.3
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• pp.127-133
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• 2020

PURPOSE: The study examined the relationship between the knee function score and knee strength and muscular endurance of an elite female handball athletes according to their position in the team. METHODS: Thirty handball athletes participated on the study: 12 front positions, 12 back positions, and five goalkeepers. The knee function score consisted of symptoms, pain, daily activity, sports and recreation, and quality of life. In addition, CSMI (Cybex, USA) was used to measure the strength and muscular endurance of the knee. The muscular strength and muscular endurance were measured at an angular velocity of 60°/s and 180°/s, respectively. RESULTS: The overall items of the knee function score showed a significant difference (p = .017), and goalkeepers had significantly higher scores than the back positions. In addition, significant differences were observed in all five items depending on the position (p ≤ .05). On the other hand, both the flexor and extensor muscles of the knee strength and muscular endurance were not significant. Moreover, there was no correlation between the knee function score and the knee strength and muscle endurance. CONCLUSION: Elite female handball athletes have different knee functions score depending on their position in the team, but the, strength and muscular endurance of the knee were similar for each position. Furthermore, the knee function score showed no correlateion with the strength and muscular endurance of the knee.

• Journal of the Korea Concrete Institute
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• v.23 no.6
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• pp.817-826
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• 2011

Concrete using eco-cement has a problem with long-term strength development. However, currently, a long-term strength development mechanism is not confirmed, resulting in a lack of application of eco-cement in construction fields. In this study, the curing humidity influence on development in long-term strength of concrete using eco-cement and the relationship between strength and pore structure were examined. The results showed that wet cured eco-cement with a high water/cement ratio showed serious long-term strength reduction due to non-reduction of pore volume (pore size over 10 nm) in mortar caste with eco-cement. Also, the study results on improvement of long-term strength of eco-cement by partial replacement with ordinary portland cement and finely-ground fly ash showed that both of these alternatives improved long-term strength of concrete caste with eco-cement due to gradual refinement of their micro-structure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.5
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• pp.110-118
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• 2010

This research dealt with the effect of steel-fiber reinforcement on the compressive strength of ultra high performance cementitious composites (UHPCC) and compared with that in normal steel-fiber reinforced concrete(SFRC). With wide range of compressive strength of UHPCC, experiments on the fiber reinforcement effect confirmed that the compressive strength in UHPCC is also improved by adding fibers as in normal SFRC. The experimental results were compared with previous researches about reinforcement effect by adding fibers, which are limited within 100MPa compressive strength. The comparison revealed the linear relationship between $f'_{cf}-f'_c$ and RI regardless of the magnitude of compressive strength, from which a general equation to express the effect of fiber reinforcement, applicable to various SFRC's with wide range of compressive strength including UHPCC.