• Journal of Digital Convergence
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• v.13 no.7
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• pp.223-228
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• 2015

This study aims to verify the effect of the strength note program by comparing and analyzing the effect of the strength note program on self-esteem and self-efficacy of university students in Convergence Age. This study targeted 70 male and female university students in G area and the subjects were asked to find their and other people's positive characteristics or strengths once a week and record them. For analysis of the collected data, frequency and percentage analysis and paired-t-test were conducted using SPSS WIN 20.0. As the result, the strength note program significantly influenced the improvement in self-esteem and self-efficacy of university students. This result demonstrates the necessity of the strength note program for improving self-esteem and self-efficacy of university students. Therefore, there is a need to provide a specific and systematic strength note program to help university students get over diverse problems. It is considered that this will help mental health, academic achievement and career search of university students and contribute to the enhancement in happiness and the quality of life. Also it will be the basis for future longitudinal studies through interdisciplinary convergency research.

• Advances in concrete construction
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• v.1 no.4
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• pp.341-358
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• 2013

Due to fast growth in urbanisation, a highly developed infrastructure is essential for economic growth and prosperity. One of the major problems is to preserve, maintain, and retrofit these structures. To meet the requirements of construction industry, the basic information on all the mechanical properties of various concretes is essential. This paper presents the details of development of various concretes, namely, normal strength concrete (around 50 MPa), high strength concrete (around 85 MPa) and ultra high strength concrete (UHSC) (around 120 MPa) including their mechanical properties. The various mechanical properties such as compressive strength, split tensile strength, modulus of elasticity, fracture energy and tensile stress vs crack width have been obtained from the respective test results. It is observed from the studies that a higher value of compressive strength, split tensile strength and fracture energy is achieved in the case of UHSC, which can be attributed to the contribution at different scales viz., at the meso scale due to the fibers and at the micro scale due to the close packing of grains which is on account of good grading of the particles. Micro structure of UHSC mix has been examined for various magnifications to identify the pores if any present in the mix. Brief note on characteristic length and brittleness number has been given.

• International Journal of Concrete Structures and Materials
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• v.7 no.3
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• pp.193-202
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• 2013

Geopolymer mortar compressed blocks were prepared using fly ash, ground granulated blast furnace slag, silica fume and metakaolin as binders and sand/quarry dust/pond ash as fine aggregate. Alkaline solution was used to activate the source materials for synthesizing the geopolymer mortar. Fresh mortar was used to obtain the compressed blocks. The strength development with reference to different parameters was studied. The different parameters considered were fineness of fly ash, binder components, type of fine aggregate, molarity of alkaline solution, age of specimen, fluid-to-binder ratio, binder-to-aggregate ratio, degree of saturation, etc. The compressed blocks were tested for compression at different ages. It was observed that some of the blocks attained considerable strength within 24 h under ambient conditions. The cardinal aim was to analyze the experimental data generated to formulate a phenomenological model to arrive at the combinations of the ingredients to produce geopolymer blocks to meet the strength development desired at the specified age. The strength data was analyzed within the framework of generalized Abrams' law. It was interesting to note that the law was applicable to the analysis of strength development of partially saturated compressed blocks when the degree of saturation was maintained constant. The validity of phenomenological model was examined with an independent set of experimental data. The blocks can replace the traditional masonry blocks with many advantages.

• Journal of International Academy of Physical Therapy Research
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• v.8 no.2
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• pp.1158-1162
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• 2017

The purpose of the study was to investigate the strength of sokinetic muscle by the position of a volleyball players. Analysis and comparison of shoulder dynamic stability will be conducted according to rotational movement of the shoulder during spiking and serving amongst the various positions. Fifty professional Korean female volleyball players (age: 20~30), all different positions - attacker (left and right), center, setter, and libero were The concentric peak torque, strength ration of the internal and external rotation of the shoulder girdle for both dominant and non-dominant arms. Firstly, there were significant differences found for the strength ratio between the setter and the other positions in the dominant arm. On a second note, there was a significant decrease in shoulder dynamic stabilization for both the attacker and center in the dominant arm. However, there were no significant differences for the setter or the libero. This study suggests that the isokinetic muscle strengths of the volleyball players are different from each other.

• Journal of Power System Engineering
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• v.22 no.6
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• pp.44-50
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• 2018

As a type of bolt with a spherical head, the ball stud is widely used as a part of a ball joint in steering or suspension systems in automobiles. Balls and studs are subjected to heat treatment suitable for each material; in particular, the shear strength of the ball stud must meet the specifications of the production company. This study evaluated the shear strength of joints according to the cooling method of ball studs subject to resistance welding. The shear stress of water cooling was higher than that of air cooling (as-received material). Note, however, th at oil cooling showed lower stress than that of as-received. When judged by standard deviation, mean, and coefficient of variation according to the arithmetic statistics and shape parameter as well as scale parameter, oil cooling is suitable.

• Textile Coloration and Finishing
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• v.34 no.3
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• pp.197-206
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• 2022

The purpose of this study was to confirm the optimal spinning conditions for PLA (Polylactic acid) as a fiber forming polymer. According to the melt spinning test results of PLA, the optimal spinning temperature was 258℃. However, it needs to note that relatively high pack pressure was required for spinning at 258℃. At an elevated temperature, 262℃, mono filament was broken easily due to hydrolysis of PLA at a higher temperature. In case of fiber strength, it was confirmed that the draw ratios of 2.7 to 3.3 were optimal for maximum strength of melt spun PLA. Above the draw ratio, 3.3, the strength of the PLA fibers was lowered. It was presumed that cleavage of the PLA polymer chain over maximum elongation. The heat setting temperature of GR (Godet roller) showed that the maximum strength of the PLA fibers was revealed around 100℃. The degree of crystallinity and the strength of the PLA fibers were decreased above 100℃. The optimal take-up speed (Spinning speed) was around 4,000m/min. Thermal analysis of PLA showed 170℃ and 57℃ as Tm (melting temperature) and Tg (glass transition temperature), respectively.

• Computers and Concrete
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• v.12 no.6
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• pp.755-774
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• 2013

Considering the well known environmental issues of cement manufacturing (direct and indirect levels of $CO_2$ emissions), clinker replacement by supplementary cementing materials (SCM) can be a very promising first step in reducing considerably the associated emissions. However, such a reduction is possible up to a particular level of SCM utilization, influenced by the rate of its pozzolanic reaction. In this study a (4-step) structured methodology is proposed in order to be able to further adjust the concrete mix design of a particular SCM, in achieving additional reduction of the associated levels of $CO_2$ emissions and being at the same time accepted from a derived concrete strength and service life point of view. On this note, the aim of this study is twofold. To evaluate the environmental contribution of each concrete component and to provide the best possible mix design configuration, balanced between the principles of sustainability (low environmental cost) and durability (accepted concrete strength and service life ). It is shown that such a balance can be achieved, by utilising SCM by-products in the concrete mix, reducing in this way the fixed environmental emissions without compromising the long-term safety and durability of the structure.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.1
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• pp.87-92
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• 2008

In the load-carrying fillet weldments, which are common in ship structures, fatigue cracks can occur at the weld root, in addition to the weld toe. In particular, fatigue cracks originating from the weld root are difficult to detect and cause a significant reduction in the fatigue strength of a weldment. Therefore, it is important to note the fatigue failure mode of load-carrying fillet weldment. In this study, a series of fatigue test was carried out for the fatigue strength evaluation of longi-web connections that are typical kinds of the load-carrying fillet weldment.

• Geomechanics and Engineering
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• v.27 no.5
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• pp.511-525
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• 2021

In the design of underground excavation, the shear strength (SS) is a key characteristic. It describes the way the rock material resists the shear stress-induced deformations. In general, the measurement of the parameters related to rock shear strength is done through laboratory experiments, which are costly, damaging, and time-consuming. Add to this the difficulty of preparing core samples of acceptable quality, particularly in case of highly weathered and fractured rock. This study applies rock index test to the indirect measurement of the SS parameters of shale. For this aim, two efficient artificial intelligence methods, namely (1) adaptive neuro-fuzzy inference system (ANFIS) implemented by subtractive clustering method (SCM) and (2) support vector regression (SVR) optimized by Harmony Search (HS) algorithm, are proposed. Note that, it is the first work that predicts the SS parameters of shale through ANFIS-SCM and SVR-HS hybrid models. In modeling processes of ANFIS-SCM and SVR-HS, the results obtained from the rock index tests were set as inputs, while the SS parameters were set as outputs. By reviewing the obtained results, it was found that both ANFIS-SCM and SVR-HS models can provide acceptable predictions for interlocking and friction angle parameters, however, ANFIS-SCM showed a better generalization capability.

• Computers and Concrete
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• v.18 no.5
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• pp.951-968
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• 2016

In this study, pullout capacities of post-installed deformed bars anchored in low strength concrete using different bonding materials are investigated experimentally. The experimental study was conducted under outdoor and indoor conditions; on the beams of an actual reinforced concrete building and on concrete bases constructed at Istanbul Technical University (ITU). Ready-mixed cement based anchorage mortar with modified polymers (M1), ordinary cement with modified polymer admixture (M2), and epoxy based anchorage mortar with two components (E) were used as bonding material. Furthermore, test results are compared with the predictions of current analytical models. Findings of the study showed that properly designed cement based mortars can be efficiently used for anchoring deformed bars in low quality concrete. It is important to note that the cost of cement based mortar is much lower with respect to conventional epoxy based anchorage materials.