• Structural Engineering and Mechanics
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• v.84 no.4
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• pp.465-477
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• 2022

The formation of biopolymer-soil matrices mainly depends on biopolymer type and concentration, soil type, pore fluid and phase transfer to influence its strengthening efficiency. In this study, the physical and mechanical properties of sodium alginate (SA) treated kaolinite are investigated through compaction test, thread rolling teat, fall cone test and unconfined compression test with considering biopolymer concentration, curing time, initial water content, mixing method. The results show that the liquid limit slightly decreases from 69.9% to 68.3% at 0.2% SA and then gradually increases to 98.3% at 5% SA. At hydrated condition, the unconfined compressive strength (UCS) of SA treated clay at 0.5%, 1%, 2% and 3% concentrations is 2.57, 4.5, 7.1 and 5.48 times of untreated clay (15.7 kPa) at the same initial water content. In addition, the optimum biopolymer concentration, curing time, mixing method and initial water content can be regarded as 2%, 28 days, room temperature water-dry mixing (RD), 50%-55% to achieve the maximum unconfined compressive strength, which corresponds to the UCS increment of 593%, compared to the maximum UCS of untreated clay (780 kPa).

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.299-300
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• 2023

In this study, the performance evaluation and structural safety of rainwater permeation detention block were analyzed. As a result, the compressive strength (19.3 MPa), flexural strength (5.2 MPa), and permeability coefficient (2.0 mm/s) of the eco-friendly prefabricated rainwater permeable detention block satisfied the KS F 4419 and SPS-KCIC0001-0703 and it was confirmed sufficient safety even under maximum load.

• Journal of Korean Association for Spatial Structures
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• v.23 no.4
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• pp.51-58
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• 2023

In this study, the displacement dependence, strength, and energy dissipation capacity of the steel rod damper were evaluated. The test variables are the number of steel rod dampers and the lateral deformation prevention details. From test results, it was evaluated that the displacement dependence conditions in the structural design code were satisfied. The maximum strength and energy dissipation capacity increased linearly as the number of steel rod increased. In addition, the maximum strength and energy dissipation capacity were evaluated by more than 20 times increased by using of the lateral deformation prevention details.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.1
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• pp.82-87
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• 2012

For different ferrite-pearlite matrix structure, contain more than 90% spheroidal ratio of graphite, GCD 45-3, GCD 50, GCD 60 series and 70%, 80%, 90% spheroidal ratio of graphite, GCD 40, GCD 45-1, GCD 45-2 series, this paper has carried out rotary bending fatigue test, estimated maximum and mean size of spheroidal graphite, investigated correlation. It was concluded as follows. (1) Fatigue limit in $10^7$cycles and numbers of spheroidal graphite per 1$mm^2$ was linear relation. (2) projection area of graphite can be used to predict fatigue limit of Ductile Cast Iron. The Statistical distribution of extreme values of projection area of defects may be used as a guideline for the control of inclusion size in the steelmaking processes.

• Journal of the Korean Ceramic Society
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• v.25 no.6
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• pp.665-670
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• 1988

The behavior of mechanical properties of ion exchanged glasses was investigated in this study. The used glasses were soda-lime-silica glasses that were produced by float process. The maximum values of the bending strength and the curvature depth are 45Kg/$\textrm{mm}^2$ and 8.6mm respectively treated at 45$0^{\circ}C$ for 6h, which are 4.4 times and 3.3 times higher than parent glass. In the case, the thermalshock resistance ΔT is 335$^{\circ}C$ that is 205$^{\circ}C$ higher than parent glass, which is the maximum values in this study. The maximum values of the surface microhardness is 490Kg/$\textrm{mm}^2$ in case of 43$0^{\circ}C$ for 4h. It is also found out that annealing points are increased linearly with increasing the amount of K+ ion exchange independent of treatment temperature. Furthermore, the present work shows that the ion exchange strengthened glasses are more effective than the physical tempering glasses ; the bending strength and the curvature depth are 1.8 times and twice higher respectively.

• Journal of the Korean Wood Science and Technology
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• v.42 no.1
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• pp.58-67
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• 2014

We investigated the mechanical properties of Korean red pine (Geumgangsong, Pinus densiflora forma erecta Uyeki) of Uljin province in Korea as a basic research to investigated the material properties. Compressive strength of Korean red pine was $36.2N/mm^2$, which was slightly lower than the pine (Pinus densiflora S. et Z.) in Korea. The compressive strength of Korean red pine showed the maximum value at a distance of 60 mm from the pith. Bending strength of Korean red pine was $76.5N/mm^2$, which was slightly higher than the pine (Pinus densiflora S. et. Z.) and nut pine (Pinus koraiensis) in Korea. Similar to the compressive strength, bending strength of Korean red pine showed the maximum value at a distance of 60 mm from the pith. On the other hand, the shearing strength showed the maximum value at part of including the pith. This result does not coincide with the results of compressive and bending strength, in consideration of the specific gravity, which is consistent. Surface hardness of Korean red pine was $43.7N/mm^2$ in cross section, $12.0N/mm^2$ in radial section and $13.7N/mm^2$ in tangential section respectively. The mechanical properties of Korean red pine were similar to the pine and nut pine having a similar specific gravity. The mechanical properties were greatly affected on the specific gravity than the annual ring width.

• The Journal of the Korea Contents Association
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• v.17 no.11
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• pp.156-166
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• 2017

The purpose of this study was to evaluate the effect of the tongue's maximum resistance training program on the accuracy of the tongue training program using the Iowa Oral Performance Instrument (IOPI) and to compare the effects of tongue muscle strength and spoken language function on objective function. The experiment was diagnosed with stroke hemiplegia divided into tongue pressure strength and accuracy training therapy group and the oromotor exercise therapy group Anterior Tongue Pressure(ATP), Posterior Tongue Pressure (PTP), and Posterior Tongue Pressure (PTP) were measured before and after the intervention to evaluate changes in tongue strength and verbal ability. Maximum Phonation Time (MPT). The results of this study are as follows. There was no significant difference in tongue strength and verbal function between training group and oral facial exercise group. There was no significant difference between tongue strength training and oral facial exercise group. Therefore, it was shown that the tongue pressure strength and accuracy training therapy group was not effective to improve tongue muscle strength and spoken language ability than the oromotor exercise therapy group.

• Journal of Welding and Joining
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• v.25 no.6
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• pp.53-58
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• 2007

The present study examined the mechanical properties of the friction welding of shaft made of SKH51 and SM45C, of which the diameter is 12mm. Friction welding was done at welding conditions of 2,000rpm, friction pressure of 104MPa, upset pressure of 134MPa, friction time of 0.5sec to 2.5sec by increasing 0.5sec, upset time of 2 seconds. Under these conditions, a tensile test, a bending test, a shear test, a hardness test and a microstructure of weld interface were studied. When the friction time was 1.0 second under the conditions, the maximum tensile strength of the friction weld observed to be 963MPa, which is 89% the tensile strength of SKH51 base metal and 101% of the tensile strength of SM45C base metal. When the friction time was 1.0 seconds under the conditions, the maximum bending strength of the friction weld happened to be 1,647MPa, which is 78% the bending strength of SKH51 base metal(2,113MPa) and 87% of the bending strength of SM45C base metal(1,889MPa). When the friction time was 1.0 seconds under conditions, the maximum shear strength of the friction weld was observed to be 755MPa, which is 92% the shear strength of SKH51 base metal and 122% of the shear strength of SM45C base metal. According to the hardness test, the hardness distribution of the weld interface varied from Hv282 to Hv327. HAZ was formed from the weld interface to 1.2mm of SKH51 and 1.6mm of SM45C. Upon examination it was found that the microstructure became finer along with increase of friction revolution radius.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.487-492
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• 2003

High-strength concrete(HSC) is a new construction material with enormous potential. Structures using high-strength concrete are to be coming more and more popular. But high-strength reinforced concrete columns show brittle behavior. It, therefore, is necessary to improve the ductility of HSC members. The purpose of this study is to investigate the ductility and strength of high-strength columns with variable lateral confinement under concentric axial load. Five HSC columns with compressive strength 68㎫ are designed with variable lateral confinements such as carbon fiber sheet(CFS), glass fiber sheet(GFS), and metal lath. Test results indicate that specimen confined by CFS show 11% higher maximum strength, 2.74 times ductility than A specimen using hoop. On comparing with the specimen A and B confined metal lath instead of hoop, strength decrease of 3%, and ductility increase of 1.21 times were observed.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.381-386
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• 2005

In order to have compressive strength tests and frost heaving tests, two sorts of soil samples at Chonbuk-Do area were used. According to this research, the compressive strength of soil which was mixed by quick lime, was largely increased until 28 days but after 28 days, the increment of strength was seldom found and its maximum compressive strength increasing rate for content of quick lime was $10{\sim}15%$ scope. In the mixed rates of quick lime and briquette ash, the compressive strength of soil which was mixed by quick lime and briquette ash, was increased by increasing mixed rates of quick lime and its compressive strength was increased by additional quantity. The compressive strength of mixed soil within freezing-thawing 1 cycle was diminished around 30% compared to non-freezing soil's 28 days compressive strength but there were no movements after 2 cycle.