• Structural Engineering and Mechanics
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• v.35 no.4
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• pp.511-533
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• 2010

As a truly meshfree method, meshless equilibrium on line method (MELM), for 2D elasticity problems is presented. In MELM, the problem domain is represented by a set of distributed nodes, and equilibrium is satisfied on lines for any node within this domain. In contrary to conventional meshfree methods, test domains are lines in this method, and all integrals can be easily evaluated over straight lines along x and y directions. Proposed weak formulation has the same concept as the equilibrium on line method which was previously used by the authors for enforcement of the Neumann boundary conditions in the strong-form meshless methods. In this paper, the idea of the equilibrium on line method is developed to use as the weak forms of the governing equations at inner nodes of the problem domain. The moving least squares (MLS) approximation is used to interpolate solution variables in this paper. Numerical studies have shown that this method is simple to implement, while leading to accurate results.

• Geomechanics and Engineering
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• v.12 no.5
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• pp.739-752
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• 2017

This study was intended to evaluate the improved strength of the ground by applying the bio grouting method to a loose sandy ground. The injection material was prepared in the form of cement-like powder, with the bio injection material produced by microbial reactions. The grouting test was conducted under the conditions similar to the field where the bio injection material can be applied. In addition, the injection materials (cement and sodium silicate No. 3) used for Labile Waterglass (LW) method and the conventional grouting methodwere prepared through a two-solution one-step process. The injection into the specimens was done at a pressure of 150 kPa and then, with a bender element, their moduliof elasticity were measured on the 7th, 14th, 21st and 28th curingdays to analyze their strengths according to the duration of curing. It was confirmed that in all injection materials the moduli of elasticity increased over time. In particular, when 30% of the bio injection material was added to 100% cement, the modulus of elasticity tended to increase by about 15%. This confirmed that the applicability became higher when the bio injection material was used in place of the conventional sodium silicate.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.3
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• pp.202-208
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• 2014

For evaluating basic structural behavior of HVFA (High Volume Fly Ash) concrete, several tests are performed considering different ratios of fly ash replacement and structural evaluation regarding compressive strength, elasticity modulus, stress-strain relationship, and bond strength is also performed. Test results show that elasticity modulus of HVFA concrete has close relationships with compressive strength and fly ash replacement ratio. The ultimate strain shows slight difference from domestic design code. On the other hand, there are no differences between general concrete and HVFA concrete for elasticity modulus and bond strength.

• Journal of Biomedical Engineering Research
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• v.28 no.1
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• pp.75-83
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• 2007

Elasticity is an important physical property of biological tissues. Differences in elasticity can help facilitate the diagnosis of tumors and their extent. Magnetic Resonance Elastography (MRE) tries to visualize images of tissue elasticity by externally applying shear stress on the surface of an imaging object. Applied shear stress induces internal displacements that can be measured from MR phase images. In order to conduct MRE imaging experiments, we need to first develop a vibrator. We found that there does not exist enough technical information to design the MRE vibrator. In this paper, we describe the theory, design and construction of an MRE vibrator. We report the performance of the developed vibrator using two different test methods. We found that the vibrator successfully induces enough internal displacements that can be imaged using an MRI scanner. We suggest future studies of numerous MRE imaging experiments using the vibrator.

• Journal of the Korean Home Economics Association
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• v.45 no.6
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• pp.49-59
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• 2007

The purposes of this study were to determine the price elasticities of foodcourt-styled university foodservice, and to identify the attributes that affect these price elasticities. Questionnaires were distributed to 700 students at the K University in Masan, from September 21-27, 2006. 478 questionnaires were ultimately included in the final analysis(response rate: 68.3%). For statistical analysis, SPSS(12.0) was used to conduct the descriptive analysis, t-test, and ANOVA. The results of this study were as follows. The average meal price for in-campus foodservice was \ 2,196 and the average meal price for an off-campus restaurant was \3,044. The university students recognized that the proper price for in-campus foodservice and an off-campus restaurant were, respectively, \2,127 and \ 2,884. The price elasticities for foodcourt-styled university foodservice were 4.20(Kko-Bul-Kko-Bul), 3.83(Il-Poom-Hyang), and 4.10(Ne-Mo-Baek_Ban). The factors that affected price elasticity included the frequency of visiting foodservice, foodservice satisfaction, price satisfaction, and customer's responses to increased meal prices. The recommended price strategy for foodcourt-styled university foodservice was to lower meal price, which would attract more students and increase the sales volume. Simultaneously, foodservice managers should attempt to improve and increase customer satisfaction and the customer's perceived value for meal price. Overall, price elasticity may prove helpful in predicting the customer's behaviors on price changes, and may provide useful basic data for foodservice managers when establishing price strategy.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09b
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• pp.147-151
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• 2010

In this study, the clay specimen of Busan-Gyeongnam region was used for unconfined compression test to compare the relationship formula between elasticity modulus at peak($E_f$), elasticity modulus at $q_u$/2($E_{50}$), and cohesion when the sample breaks down by region and by level of cohesion. As the result, the regional results were found to be in the range of $E_f$ = 14c~47c and $E_{50}$ = 43c~137c; by cohesion, the results for very soft ground was $E_f$ = 15c~40c and $E_{50}$ = 54c~101c, $E_f$ = 13c~63c and $E_{50$ = 40c~147c for soft ground, $E_f$ = 18c~47c and $E_{50}$ = 57c~144c for medium ground, and $E_f$ = 25c~45c and $E_{50}$ = 68c~115c for solid ground. The average of the relationship formula between elasticity modulus-cohesion for the clay used in this study was $E_f$ = 32c, $E_{50}$ = 93c. This is 2.5~5 times smaller than the existing relationship formula.

• Journal of the Korea Concrete Institute
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• v.28 no.2
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• pp.213-221
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• 2016

Uniaxial compression tests for ultra-high performance hybrid steel fiber reinforced concrete (UHPC) were performed to evaluate the compressive behavior of UHPC. The UHPC for testing contains hybrid steel fibers with a predetermined ratio using a length of 19 mm and 16 mm straight typed steel fibers. Test parameter was determined as a fiber volume ratio to investigate the effect of fiber volume ratio on the strength and secant modulus of elasticity. Test results showed that the compressive strength and elastic modulus of UHPC increased with increasing the fiber volume ratio. Based on the test results, the compressive strength and modulus of elasticity equations were proposed as function of the compressive strength of unreinforced and fiber reinforced UHPC, respectively. The simplified equations for predicting the mechanical properties of the UHPC were a good agreement with the test data. The proposed equations are expected to be applied to the SFRC and UHPC with steel fibers.

• Smart Structures and Systems
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• v.17 no.4
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• pp.593-610
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• 2016

In this study, an innovative and smart glass fiber-reinforced polymer (GFRP) hybrid bar was developed for stronger durability of concrete structures. As comparing with the conventional GFRP bar, the smart GFRP Hybrid bar can promise to enhance the modulus of elasticity so that it makes the cracking reduced than the case when the conventional GFRP bar is used. Besides, the GFRP Hybrid bar can effectively resist the corrosion of conventional steel bar by the GFRP outer surface on the steel bar. In order to verify the bond performance of the GFRP hybrid bar for structural reinforcement, uniaxial pull-out test was conducted. The variables were the bar diameter and the number of strands and pitch of the fiber ribs. Tensile tests showed a excellent increase in the modulus of elasticity, 152.1 GPa, as compared to that of the pure GFRP bar (50 GPa). The stress-strain curve was bi-linear, so that the ductile performance could be obtained. For the bond test, the entire GFRP hybrid bar test specimens failed in concrete splitting due to higher shear strength resulting in concrete crushing as a function of bar deformation. Investigation revealed that an increase in the number of strands of fiber ribs enhanced the bond strength, and the pitch guaranteed the bond strength of 19.1 mm diameter hybrid bar with 15.9 mm diameter of core section of deformed steel the ACI 440 1R-15 equation is regarded as more suitable for predicting the bond strength of GFRP hybrid bars, whereas the CSA S806-12 prediction is considered too conservative and is largely influenced by the bar diameter. For further study, various geometrical and material properties such as concrete cover, cross-sectional ratio, and surface treatment should be considered.

• Journal of Energy Engineering
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• v.21 no.3
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• pp.301-308
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• 2012

This paper attempts to estimate the demand function for the transport LPG and to analyze long-run and short-run price and income elasticities. In addition, the paper measures consumer surplus and economic value ensuing from the transport LPG consumption by utilizing the estimated long-run price elasticity. The price and the income data are the monthly real transport LPG price and the monthly composite index adjusted by real transport LPG price from 2003 to 2012. Unit root test, co-integration test and error correction model are to take the procedure of estimation of demand curve. The demand for transport LPG is considered to be inelastic and the long-run demand is more elasticity than that of short-run. Price elasticity of demand estimate here is -0.422, and the estimated consumer surplus and economic value in 2010/03 are 966 and 1,781 billion won, respectively.

• Korean Journal of Food Science and Technology
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• v.15 no.3
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• pp.295-301
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• 1983

The mechanical models representing the theological property of traditional Korean noodles; i.e. wheat flour noodle and wheat-sweet potato starch noddle, were investigated from the data obtained by creep and creep recovery test using a tensile tester. The rheological behavior of the noodle products could be expressed by the 6-elements Voigt model. The instantaneous elasticity, retarded elasticity, retardation time, retarded viscosity and Newtonian viscosity of the noodle products were evaluated. With the increasing cooking time, 4-elements Burger's model was applicable to represent the mechanical behavior of wheat-sweet potato starch noodle.