• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.429-432
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• 2006

The shrinkage mechanism of high strength concrete is different from that of normal concrete. The shrinkage of normal concrete is subjected to evaporate moisture in concrete, but most shrinkage in high strength concrete is caused by chemical reaction. To analyze shrinkage of concrete exactly, it is necessary to divide drying shrinkage with autogenous shrinkage in terms of degree of hydration, especially in concrete with low W/C ratio. The proposed method can provide a rational basis for prediction of shrinkage in high strength concrete structure.

• 동력기계공학회지
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• 제9권4호
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• pp.83-89
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• 2005

Molding shrinkage is one of the problems to be solved in conventional injection molding. Despite many trying-out has been to solve it, intrinsic cause of shrinkage such as orientation and thermal exchange between melt and mold has not been solved yet. For reducing shrinkage and residual stress on molding, injection compression molding process was invented. In this study, experiments about effects of injection compression molding's parameters on shrinkage of PMMA molding were conducted and compared with conventional injection molding's shrinkage. Before the injection compression molding experiment, molding shrinkage rate was predicted by analyzing pvT diagram and was compared with the results of experiment. The shrinkage rate of injection compression molding was lower than convention injection molding's one which was different from the predicted shrinkage. The reason was observed that the experimental mold was not a proper type for injection compression, flowing backward of melt into nozzle and unreasonable mechanism of injection molding machine.

• Journal of Welding and Joining
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• 제5권3호
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• pp.46-52
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• 1987

The mechanism of transverse shrinkage for the butt joint weldig of plates is investigated in this paper. It was certified that the compressive plastic strain due to thermal expansion of materials during heating play an important role on the transverse shrinkage. It was also pointed out that the transverse shrinkage has to be treated with the samples of which the shapes are as close to real shapes of welded materials as possible, because the distribution of temperature and relative rigidity of materials during welding have great influence on the transverse shrinkage. The formulas for the calculation of transverse shrinkage were presented and the experiments were carried out in order to verify the formulas. the main results are as follows; 1. For the bead-on-plate welding, the transverse shrinkage in the begining parts of welding is the smallest, the end parts is next and the transverse shrinkage of mid section is the largest. 2. In bead-on-plate welding, the equations presented in this paper concerning transverse shrinkage coincide fairly well with the experimental values generally. 3. Transverse shrinkage increases generally as specific heat input per unit thickness increaes.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.589-592
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• 2005

Molding shrinkage s variation is one of the problems to be solved in conventional injection molding. Despite many trying-out has been to solve these, intrinsic causes of shrinkage such as orientation and thermal exchange between melt and mold has yet not solved. For reducing shrinkage and residual stress on molding, injection compression molding process was invented. In this study, experiments about effect of injection compression molding's parameters on shrinkage of molding were conducted with PMMA and compared with conventional injection molding's shrinkage. Before the injection compression molding experiment, molding shrinkage rate was predicted by analyzing pvT graph and was compared with the results of experiment. The shrinkage rate of injection compression molding was lower than convention injection molding' one but was different from the predicted shrinkage. The reason was observed that experiment mold as not positive type, flowing backward of melt into nozzle and unreasonable mechanism of injection molding machine.

• 대한전자공학회논문지
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• 제25권7호
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• pp.767-773
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• 1988

We have proposed a new simple and easy method for the observation of OSF growth and shrinkage. This method is to observe the behavior of OSF in thedamaged region during oxidation as well as annealing process after introducing mechanical damage on the silicon surface by pressure-controllable indentor. The effect of SiO2 layer on the shrinkage of pregrown OSF generated by the proposed method has been investigated using the samples with or without SiO2 layer. From the experimental data, we suggest a model for the shrinkage of OSF, which is based on the recombinaiton mechanism between silicon interstitial and vacancy at the Si-SiO2 interface.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2006년도 춘계학술논문 발표대회 제6권1호
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• pp.97-100
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• 2006

This paper report the result of the investigation on the properties of drying shrinkage for alkali-activated slag mortar in different relative humidity Commonly we know that drying shrinkage means lost more moisture but the mechanism of drying shrinkage of alkali activated slag mortar is not entirely due to the quantity of weight loss of water from mortar. pore size distribution and the calcium silicate hydrate gel characteristics have a critical influence on the magnitude of drying shringkage to alkali activated slag mortar. For this investigation, Ca(OH)2, Na2SiO4 were as alkali activator with 5 dosages(6%, 9%, 12%, 15%, 20%) and curing condition were three different relative humidity(35%, 65%, 95%) at $20{\pm}3^{\circ}C$

• Ocean and Polar Research
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• 제26권4호
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• pp.679-684
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• 2004

To determine if Antarctic krill employ body shrinkage as one of its overwintering mechanisms in the field, Euphauia superba and Euphausia crystallorophias were collected during fall and winter in and around Marguerite Bay through US Southern Ocean GLOBEC field programs during fall and winter 2001 and 2002. The relationships between the body length and weight of both krill species were exponentially correlated with no significant differences between the two species (p>0.05). The ratio between eye diameter and body length of individual krill was examined in an expectation that it could be used as an indicator of the body shrinkage as previously suggested by Shin and Nicol (2002). These ratios were significantly different between the two krill species. Especially, E . crystallorophias had bigger eyes than E. superba. In both krill species, eye diameters were highly correlated with body lengths (regression coefficients ${\geq}0.70$). For E. crystallorophias, no significant differences of the ratio of eye diameter/body length were detected between fall and winter. Even though the ratios for E. superba were seasonally varied, it was not clear whether body shrinkage was an actual and critical overwintering mechanism for the krill population found in this study area. These results suggest that some individuals of E. superba might experience the body shrinkage during a part of their liff, but this morphological index alone (eye diameter/body length) may be insufficient to unambiguously separate the shrunk krill from the non-shrunk ones in the field-collected animals.

• 펄프종이기술
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• 제43권4호
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• pp.49-58
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• 2011

The maximum drying shrinkage velocity was proposed to verify bulk and stiffness improvement mechanism during drying according to papermaking parameters. It was based on the wet-web shrinkage behavior without the restraint of wet-web during drying, so intact drying impact could be measured. Bulking agent reduced the drying shrinkage and the maximum drying shrinkage velocity, so paper bulk increased and paper strength decreased. When adding cationic starch to stock with the bulking agent for strengthening, the bulk was increased further with additional decreasing of the drying shrinkage and the maximum drying shrinkage velocity. Paper strength also increased except tensile stiffness index with decreasing the drying shrinkage and the maximum drying shrinkage velocity. When using additional strength additives for strengthening of fiber interfaces extended by bulking agent and cationic starch, amphoteric strength additive increased paper stiffness without loss of paper bulk. It was considered that the added amphoteric strength additives were cross-linked to the stretched cationic starch and this cross-linking increased elasticity of fiber-polymer-fiber interfaces without changing the drying behavior. Paper bulk could be increased with decreasing the maximum drying shrinkage velocity. The drying shrinkage of paper also could be controlled by fiber-to-fiber bonding interfaces by the bulking agent. In this case, paper strength including stiffness was decreased by reducing fiber-to-fiber bonding but it could be improved by strengthening fiber-to-fiber interfaces with polymer complex without loss of bulk.

• 한국구조물진단유지관리공학회 논문집
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• 제20권5호
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• pp.102-108
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• 2016

이 연구의 목적은 개착식 전력구 콘크리트에 발생하는 부등건조수축에 의한 균열특성을 파악하고, 수축저감제 혼입에 따른 건조수축균열특성을 분석하는데 있다. 따라서 이 연구에서는 전력구 박스형 콘크리트 구조물의 부등건조수축에 의한 균열특성을 파악하기 위하여 세 가지 주요영향인자를 고려한 수치해석과 수치해석을 한 결과와 실제 전력구 타설을 하여 측정한 차이를 확인해 보았다. 본 연구로부터 건조 수축 시험체에 대한 건조수축량을 산정에 대한 해석 기법을 개발하였으며, 실제 전력구 타설 실험을 통해 종방향 및 횡방향 균열발생 가능성을 입증 하였다. 전력구 실증시험체 건조수축량 수치해석 결과, 균열저감 콘크리트 배합의 경우 종방향 및 횡방향 응력에 있어 일반배합에 비해 40~50%정도의 현저한 감소를 보이며, 이에 따라 균열저감 콘크리트를 전력구에 적용하였을 경우 현저한 균열감소 효과를 보일 것으로 예측된다.

• Transactions on Electrical and Electronic Materials
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• 제12권1호
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• pp.32-34
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• 2011

A zero-shrinkage sintering process in which the shrinkage of the x-y axis is controlled to be zero is in great demand due to the high integration trend in ceramic modules. Among the zero-shrinkage sintering processes available, the glass infiltration method proposed in the preliminary study with an $Al_2O_3/Glass/Al_2O_3$ structure is one promising method. However, problems exist in regard to the glass infiltration method, including partially incomplete joining between $Al_2O_3$ and glass layers due to the precipitate of Ti-Pb rich phase during the sintering process. Therefore, we wish to solve the de-lamination problems and suggest a mechanism for delamination and the solutions in the zero-shrinkage low temperature co-fired ceramic (LTCC) layers. The de-lamination problems diminished using the Pb-BSi-O glass without $TiO_2$ in Pb-B-Ti-Si-O glass and produced a very dense zero-shrinkage LTCC.