• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.51-58
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• 1997

An experimental study was performed to discover the tribological behaviors of pure tin and zinc coated 52100 bearing steel. Pure tin coatings ranging from 30 nm to 30,000 nm and pure zinc coatings ranging from 500 nm to 52,000 nm were produced by a thermal evaporation coating method. Experiments using a thrust ball bearing-typed rolling test-rig were performed for the investigations of the effect of coating thickness on the tribological rolling behavior. Results showed that the existence of optimum film thickness which revealed minimum rolling resistance was discovered for tin and zinc coating. The compatibility of coating matehal to iron showed no significant effect on the rolling resistance behavior. The hardness of coating material revealed significant influence to the rolling resistance behavior.

• Journal of Mechanical Science and Technology
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• v.14 no.10
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• pp.1041-1050
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• 2000

In this paper the effect of specimen thickness on fatigue crack growth with the spatial distribution of material properties is presented. Basically, the material resistance to fatigue crack growth is treated as a spatial stochastic process, which varies randomly on the crack surface. The theoretical autocorrelation functions of fatigue crack growth resistance with specimen thickness are discussed for several correlation lengths. Constant ${\Delta}K$ fatigue crack growth tests were also performed on CT type specimens with three different thicknesses of BS 4360 steel. Applying the proposed stochastic model and statistical analysis procedure, the experimental data were analyzed for different specimen thicknesses for determining the autocorrelation functions and probability distributions of the fatigue crack growth resistance.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.24 no.4
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• pp.35-37
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• 1979

To investigate the genetic system in resistance to powdery mildew winter wheat cultivar Diplomat which has stable field resistance was crossed with high yielding susceptible winter type Caribo and Hayman's generation mean analysis technique was employed. Mildewing rate on flag-leaf at both heading-flowering and ripe stages were recorded according to lame's quantitative scale. The result indicated that additive gene effect was more important and significant role in the inheritance of resistance while dominant gene effect was minimum, and digenic interations were absent. Narrow sense heritability of resistance at ripe stage was higher than that of heading-flowering stage.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.11
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• pp.2967-2972
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• 1994

The multiple character of the contact interaction and the collective behavior of elementary microcontacts play a significant role in all the processes occurring in the surface layers, including the failure due to friction and wear. The array of metal spheres compressed between flat plates has been used for simulation of the contact behavior of multiple contact of solids under normal loading. An experimental design has been made providing regular array of the spheres at the same size with different spatial order. Measurement of electrial contact resistance has been made using the equipment providing the adequate accuracy in the range of micro Ohms. The data on electrical contact resistance have been compared with theoretical predictions using the multiple contact model of constriction resistance. The effect of single spots number and array on conductivity of contact has been evaluated.

• Journal of Ocean Engineering and Technology
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• v.26 no.6
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• pp.14-18
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• 2012

A 30ft class aluminum leisure boat is newly developed and the resistance performances are investigated by a model test at a high-speed circulating water channel. The effect of a fin attached to the side of the hull is studied at two different displacements. Wave patterns are observed to make clear the relationship between the resistance performance and wave characteristics. It can be found that a chine position at the draft line can have a strong effect on the resistance performance around a certain velocity range.

• Elastomers and Composites
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• v.50 no.3
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• pp.159-166
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• 2015

Silica which is used for reinforcing filler in tire industry is widely known as eco-friendly material exerting $CO_2$ reduction effect through decrease of rolling resistance and improvement of wet grip. Generally silica is classified as a highly polar filler because it contains a large number of silanol (Si-OH) group on its surface. And also silica gives a lower reinforcing effect than carbon black due to its poorer rubber-filler interaction. Therefore silica is treated with silane coupling agent or activator, then following the conventional rubber blend method, vulcanized sheets were prepared using a hot press, and cure characteristics, mechanical properties and abrasion resistance of the test specimens were investigated. It was found that with an increase in the silane coupling agent content the tensile strength, 300% modulus and abrasion resistance increased while Mooney viscosity decreased and crosslink density slightly increased with an increase of activator.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.163-164
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• 2017

The paper is to investigate the effect of spreading of various kinds of oils on resistance to chloride attack of the normal strength concrete. Resistance to chloride attack was measured for 32 weeks and six different kinds of oils ere used. Test results indicated that resistance to chloride attack was improved in order of DSP, BD, ERBD and ERCO compared with that of Plain mixture due to filling effect of capillary pore by the use of oil.

• Journal of Ocean Engineering and Technology
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• v.8 no.2
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• pp.47-55
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• 1994

The purpose of the present study is to investigate the effect of specimen thickness on statistical properties of crack growth resistance. In this study, the resistance S$\delta$$_h$(x) to fatigue crack growth was treated as a spatial stochastic process. which varies randomly on the crack surface. The theoretical autocorrelation functions of the resistance to fatigue crack growth considering specimen thickness are discussed for several correlation lengths. The main results obtained are : (1) The theoretical autocorrelation functions of S$\delta$$_h$(x) are almost independent of specimen of specimen thickness except for the origin. (2) The variance increases with decreasing specimen thickness.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.611-618
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• 2005

In this research, the effect of rock mass weathering on the side shear resistance of drilled shaft socketed into weathered rock was investigated. For that, a database of 23 cast-in-place concrete piles with diameters varying from 400mm to 1,500mm were socketed into weathered igneous/meta-igneous rock at four different sites. The static axial load tests were performed to examine the resistant behavior of the piles, and a comprehensive field/laboratory testing program at the field test site was also performed to describe the in situ rock mass conditions quantitatively. No correlation was found between the compressive strengths of intact rock and the side shear resistance of weathered/soft rock. The ground investigation data regarding the rock mass conditions (e.g. $E_m,\;E_{ur},\;_{plm}$, RMR, RQD, j) was found to be highly correlated with the side shear resistance, showing the coefficients of correlation greater than 0.7 in most cases. Additionally, the applicability of existing methods for the side shear resistance of piles in rock was verified by comparison with the field test data. The existing empirical relations between the compressive strength of intact rock and the side shear resistance(Horvath (1982), Rowe & Armitage(1987) etc.) appeared to overestimated the side shear resistance of all piles tested in this research unless additional consideration on the effect of rock mass weathering or fracturing was applied. The existing methods which consider the effect of rock mass condition were modified and/or extended for weathered rock mass where mass factor j is lower than 0.1, and RQD is below 50%.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.3
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• pp.125-134
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• 2021

Purpose : This study applies inspiratory muscle resistance exercise with aerobic exercise to smokers and nonsmokers and then determines whether subjects' breathing functions (FVC, FEV1) are increased and how much effect smoking has on the difference in the increase of breathing functions between the two groups. Methods : For this experiment, 26 male adults were selected and randomly allocated to the smoker group (n=13) and nonsmoker group (n=13). The smokers and nonsmokers performed the inspiratory muscle resistance exercise with aerobic exercise three times a week for four weeks. Regarding the breathing functions, the forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were measured three times: week 0, week 2, and week 4. The aerobic exercise was performed using a stationary bicycle with 8 difficulty levels. The inspiratory muscle resistance exercise was performed using Power Breathe with 10 resistance levels. Results : The study found that the FVC and FEV1 values of the smoker group decreased slightly after four weeks of inspiratory muscle resistance exercise with aerobic exercise. In other words, the difference was not statistically significant. In contrast, the FVC and FEV1 values of the nonsmoker group increased by a statistically significant amount. In addition, the intergroup comparison of the average increases in FVC and FEV1 values showed statistically significant differences. Conclusion : The results of this study show that when inspiratory muscle resistance exercise with aerobic exercise was performed, the increase in the breathing functions of nonsmokers was higher than that of smokers. This confirms that, within the parameters of the study, smoking had a negative effect on the increase of breathing functions. This suggests that quitting smoking must be considered as an essential factor when applying a breathing physiotherapy or a breathing function improvement program in clinical settings