• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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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.

• 한국농공학회지
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• 제30권1호
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• pp.38-49
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• 1988

This paper presented as follows results of laboratory model tests with various shaped footings on soil bed reinforced with the strips on the base of behaviour of soil structure according to the loads and triaxial test results reinforced with geotextiles. Their parameters studied were the effects on the bearing capacity of a footing of the first layer of reinforcement, horizontal and vertical spacing of layers, number of layers, tensile strength of reinforcement and iclination load to the vertical 1.Depending on the strip arrangement, ultimate bearing capacity values could be more improved than urreinforced soil and the failure of soil was that the soil structure was transfered from the macrospace to microspase and its arrangement, from edge to edge to face to face. 2.The reinforcement was produced the reinforcing effects due to controlling the value of factor of one and permeable reinforcement was never a barrier of drainage condition. 3.Strength ratio was decreased as a linear shape according to increment of saturation degree of soil used even though at the lower strength ratio, the value of M-factor was rot influenced on the strength ratio but impermeable reinforcement decreased the strength of bearing capacity. 4.Ultimate bearing capacity under the plane-strain condition was appeared a little larger than triaxial or the other theoretical formulars and the circular footing more effective. 5.The maximum reinforcing effects were obtained at U I B=o.5, B / B=3 and N=3, when over that limit only acting as a anchor, and same strength of fabric appeared larger reinforcing effects compared to the thinner one. 6.As the LDR increased, more and more BCR occurred and there was appeared a block action below Z / B=O.5, but over the value, decrement of BCR was shown linear relation, and no effects above one. 7.The coefficient of the inclination was shown of minimum at the three layers of fabrics, but the value of H / B related to the ultimate load was decreased as increment of inclination degree, even though over the value of 4.5 there wasn't expected to the reinforcing effects As a consequence of the effects on load inclination, the degree of inclination of 15 per cent was decreased the bearing capacity of 70 per cent but irnproved the effects of 45 per cent through the insertion of geotextile.

• Advances in concrete construction
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• 제11권5호
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• pp.429-445
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• 2021

With regard to economic efficiency, composite fix beams are widely used to pass longitudinal shear forces across the interface. The current knowledge of the composite beam load-slip activity and shear capability are restricted to data from measurements of push-off. Modelling and analysis of the composite beams based on Euro-code 4 regarding to shear, bending, and deflection under differing loads were carried out using Finite Element through an efficient computer simulation and the final loading and sections capacity based on the failure modes was analysed. In bending, the section potential was increased by an improvement of the strength in both steel and concrete, but the flexural and compressive resistance growth is very weak (3.2% 3.1% and 3.0%), while the strength of the concrete has increased respectively from 25 N/mm² to 30, 35, and 40 N/mm² compared to the increment of steel strength by 27% and 21% when it was raised from 275 to 355 and 460 N/mm², respectively. It was found that the final flexural load capacity of fix beams was declined with increase in the fix beam span for both three steel strength. The shear capacity of sections was remained unchanged at constant steel strength and different length, but raised with final yield strength increment of steel sections by 29%, and 67% when it was raised from 275 N/mm² to 355 N/mm² and 460 N/mm², respectively.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2003년도 춘계공동학술대회논문집
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• pp.21-26
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• 2003

지금까지의 탄성설계 개념에서 진전하여 소성을 고려한 탄소성 설계 개념의 설계적용이 필요하다 본 연구에서는 선체의 대표적인 구조물인 판을 대상으로 일반적인 하중형증분법 및 변위형증분법과 같은 비선형해석 기법과 호장증분법과 Newton-Raphson법을 병용한 증분형해법을 비교하였다. 특히. 초기처짐의 형태에 따른 해석을 통하여 초지처짐의 형상에 따른 판의 탄소성거동을 규명하였다 압축하중을 받는 박판구조물은 초기좌굴후 거동과 2차좌굴후 거동이 구조물 전체에 미치는 영향이 매우 크며 이러한 복잡한 거동을 구하기 위해서 해석방법으로는 범용 유한요소해석 프로그램인 ANSYS를 이용하였고 특히 호장증분법은 좌굴점에서의 복잡한 비선형 거동을 추정하기 위하여 적용하였다.

• 한국산업융합학회 논문집
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• 제11권1호
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• pp.35-40
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• 2008

Various characters of the concrete are greatly improved as the effect of the steel fiber. As the improvement effect of the steel fiber, the increment in flexural strength, shear strength, toughness, and impact strength are remarkable, and tenacious concrete is obtained. This paper presents model which can predict mechanical behavior of the structure according to aspect ratio and volume fraction of steel fiber. Experiments on compressive strength, elastic modulus and tensile strength were performed with self-made cylindrical specimens of variable aspect ratios. This paper presents an analytical study on the behavior of a beam specimen with steel fiber reinforced concrete(SFRC). The effect of the SFRC on the crack pattern, failure mode and the flexural behavior of the structure were investigated. The analysis model based on the nonlinear layered finite element method was successfully able to find the necessary amount of steel fibers, tensile steels and beam section which can best approximate flexural strength and ductility of a given conventionally reinforced concrete beam.

• 대한임상전기생리학회지
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• 제3권1호
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• pp.49-59
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• 2005

This study assigns each 8 of 24 normal persons to control group(Group I), strength increase group(Group II) and endurance increase group(Group III) to analyze differences in changes of strength and endurance with surface electromyography and kinetics according to application modes of neuromuscular electrical stimulation(NMES). Group I had not any treatment, group II performed 15 repeated contraction with 60% intensity of maximal voluntary isometric contraction(MVIC) by setting 10-sec on time and 50-sec off time and group III conducted 30 repeated contraction with 30% intensity of MVIC by setting 10-sec on time and 20-sec off time. For neuromuscular electrical stimulation, 2,500 Hz of Russian current, 35 pps of pulse rate and 200 of pulse width. Neuromuscular electrical stimulation was conducted by five times for total 4 weeks. Before and after experimentmotor unit action potential of vastus medialis, rectus femoris and vastus lateralis were measured with sEMG, median frequency(MDF) was analyzed, and thus the following results were obtained. There was significant difference in the period of measuring vastus medialis and rectus femoris in change of MDF and interaction among groups with analysis of surface electromyography before and after neuromuscular electrical stimulation(p<.001) and in particular, there was a remarkable change among groups according to the period of measurement. In conclusion, NMES influenced changes of strength and endurance according to its application modes and in particular, it was found that strength increment application had a significant influence on strength increment in applying short-time NMES.

• Steel and Composite Structures
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• 제10권6호
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• pp.501-516
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• 2010

This paper is aiming to study the performances of reinforced high-strength concrete (HSC) short columns confined with aramid fibre-reinforced polymer (AFRP) sheets. An experimental program, which involved 45 confined columns and nine unconfined columns, was carried out in this study. All the columns were circular in cross section and tested under axial compressive load. The considered parameters included the concrete strength, amount of AFRP layers, and ratio of hoop reinforcements. Based on the experimental results, a prediction model for the axial stress-strain curves of the confined columns was proposed. It was observed from the experiment that there was a great increment in the compressive strength of the columns when the amount of AFRP layers increases, similar as the ultimate strain. However, these increments were reduced as the concrete strength increasing. Comparisons with other existing prediction models present that the proposed model can provide more accurate predictions.

• E2M - 전기 전자와 첨단 소재
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• 제5권4호
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• pp.393-399
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• 1992

In order to increase the coupling strength between bisphenol-A type epoxy resin and filler SiO$_{2}$ it was treated to filler with silane coupling agent[KBM-603]. To observe how silane coupling agent effects on dielectric breakdown strength of Epoxy/SiO$_{2}$ compound material, specimens of eight type were made like following. (A-1, A-2), (B-1, B-2), (C-1, C-2), (D-1, D-2) (see 2-2. Specimen) Specimen treated with silane coupling agent had always bigger dielectric breakdown strength than non-treated specimen. Under the influence of silane coupling agent, increment ratio of dielectric breakdown strength at specimen manufactured by hand drill was very bigger than that of specimen inserted spherical electrode. Therefore, as the specimen shape was varied, it was studied on effect that silane coupling agent affects on dielectric breakdown strength of Epoxy/SiO$_{2}$ compound material.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.67-70
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• 2005

In this study, an experimental investigation of the strength of R/C columns with 300mm square sections confined by head anchorage bar is presented. This initial phase of research considers only axial loading and consists of a total of 7 column tests. The main variables are distance and anchorage type of transverse reinforcement such as standard hooks and headed bar. The purpose of this study is to investigate the confinement effect and strength increment by head and to propose the confinement model for column using the head at end of lateral tie. Also, the test results for ultimate strength and strength gain factor of columns in this study and previous study is compared with the existing analytical models. Based on the test results, the Saatcioglu's model estimates confinement effects was closed to experimental value and the developed analytical approach considered the head was capable of predicting the strength gain factor results with a resonable accuracy.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.796-799
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• 2005

In 2005, a regulation on the heavy-weight impact sound was released, which restricted concrete slab thickness of standard floor to 210mm. To reduce heavy-weight impact sound, damping materials and structural reinforcement system have been proposed. In this study, the effect of compressive strength on the heavy-weight impact vibration and sound were investigated. FEM analysis was conducted for the 34PY apartment with different concrete strength (210, 350, 420kg/cm$^2$). In addition, apartment floors with different concrete strength were constructed and the floor impact vibration and sound were measured. Results of FEM analysis and measurement show that the resonance frequency of concrete slab was increased by the increment of concrete strength. However, floor impact sound pressure level did not decrease because the nor impact vibration and sound pressure level in 63Hz band increased.