• 한국세라믹학회지
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• 제39권11호
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• pp.1083-1089
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• 2002

알루미나 세라믹스에 MgO와 $TiO_2$를 각각 단독으로 첨가했을 때의 치밀화와 소결 거동을 수축률-소결 밀도 관계를 통해 비교 조사하였다. MgO가 첨가되었을 때는 소결 전과정을 통해 입성장은 억제되고 치밀화는 촉진되었으나, $TiO_2$가 첨가되었을 때는 입성장은 촉진된 반면 치밀화는 떨어졌다. 또한 입자 크기, 밀도, 수축률등을 통해 수축률-소결 밀도 관계를 구하여 최대 수축률을 나타내는 밀도값(Density of Maximum Shrinkage Rate:${\rho}$J.S.R)을 조사해 보았다. 이때 최대 수축률을 나타내는 밀도값보다 낮은 밀도를 보이는 영역에서는 치밀화가 입성장보다 우세하게 진행되었으며 최대 수축률을 나타내는 밀도값보다 높은 밀도의 영역에서는 입성장이 보다 우세하게 진행되는 것으로 추정하였다. 이때 최대 수축률을 나타내는 밀도값은 $TiO_2$가 첨가된 알루미나 < 순수 알루미나 < MgO가 첨가된 알루미나의 순서로 높은 값을 보였다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.351-355
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• 2003

Recently, the Rapid Prototyping System makes used of changing file format. The most problem is produced by this process. It is influenced by the precision of shape manufacturing. And It is most influenced by shrinkage rate within many elements influence the precision of 3D shape manufacturing. In result, the length strain in each axis cause at STL file transforming. It will compensate for utilizing the shrinkage rate.

• 한국정밀공학회지
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• 제22권7호
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• pp.177-184
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• 2005

Recently, the engineering designer of injection mould has become more and more dependent on the CAE. In the design factors of injection mould, the shrinkage rate should be considered as one of the important performances to produce the reliable products. therefore the shrinkage rate can be mostly calculated by the MoldFlow and Pro-engineering. in the design process. However it is not easy to predict the shrinkage rate of a plastic injection mold in its design process because the analysis can take minutes to hours, the high computational costs of performing the analysis limit their use in design optimization. In this study, the surrogate models, DACE model, based on the Kriging in order to optimize the shrinkage rate of electric microwave oven window is used in lieu of the original models, facilitating design optimization.

• Journal of Mechanical Science and Technology
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• 제14권1호
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• pp.65-71
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• 2000

Mold cavities of gears should be made larger than the product specification since plastics shrink when changing from a molten to a solid state. For injection molded spur gears, two design methods for the compensation of shrinkage are widely used. One is the module correction method and the other is the pressure angle correction method. Both methods are based on the assumption that shrinkage occurs toward the center of a molded gear. This paper deals with the shrinkage rate and proposes a method of designing gear cavity derived from the measured shrinkage rates which govern the outside diameter, the tooth depth and the tooth thickness of a molded gear. The proposed method imposes no restriction on the shrinkage direction and provides a cavity with all of the fundamental gear design parameters.

• 한국의류학회지
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• 제2권2호
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• pp.209-215
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• 1978

This experiment was designed to analyze the factors, which are very common in practical sewing, affecting on sewing shrinkage by using orthogonal array ($L_{27}$) table. The results were analyzed by using the computer program, PDP 11/10. The results showed that sewing shrinkage was increased up to 3 times of laundrying but no further changes could be found. Sewing shrinkage was affected much by the number of stitching and yarn tension and the rate increased with proportion to the number of stitching in unit length and yarn tension. When cotton yarn was used in P/C fabrics, the shrinkage was much smaller, but this results did not agree with other articles reported. Sewing by using $\sharp$11 needle and 1000$\~$1500r.p.m. seemed to lower the shrinkage rate.

• 콘크리트학회지
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• 제8권1호
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• pp.111-120
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• 1996

콘크리트의 건조수축 특성은 콘크리트 구조물의 내구성을 결정하는 대단히 중요한 특성으로서 환경적인 요인에 영향을 많이 받는다. 이 환경적 요인은 온도, 습도, 풍속 등으로 구성되어 있는데 이들 개별적인 인자들은 변화폭이 크로, 콘크리트의 건조에 미치는 영향이 복합적이기 때문에 이들의 영향을 개별적으로 평가하는 것은 큰 의의가 없다. 본 연구에서는 건조수축에 영향을 미치는 환경적인 요인들을 통합하고자 증발속도라는 변수를 도입하였다. 적절한 온도와 습도, 풍속, 콘크리트 온도 등을 선정하여 선정된 환경하에서의 증발속도를 증발속도계로 측정하였으며, 이 결과를 기존의 PCA 도표와 비교 평가하였고, 설정된 조건하에서의 실험을 통하여 콘크리트의 건조수축과 증발속도간의 관계를 규명하였다. 또한 건조수축 실험결과와 이 변수 사이의 관계를 정량화하여 건조수축의 예측에 이용될 수 있는 예측모델식과 도표를 개발하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 추계 학술논문 발표대회
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• pp.85-88
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• 2008

As super-high-strength concrete uses a large amount of binder, there is an autogenous shrinkage strain larger than dry shrinkage and it degrades the quality of structures. Thus, we need a technology to minimize the shrinkage strain of super-high-strength concrete. Accordingly, the present study prepared super-high-strength concrete with design strength of over 100MPa and, using an embedded gauge, measured the shrinkage strain of free shrinkage specimens for super-high-strength concrete containing expansion agent. According to the results of this study, the expansion rate of concrete increased in the early stage due to the admixture of expansion agent, but the shrinkage rate went down with the lapse of time. The effect of the admixture of expansion agent on compressive strength appeared insignificant. Further research shall be made on different kinds of expansion agents and various mixture ratios for basic analysis to reduce autogenous shrinkage of super-high-strength concrete.

• 복식문화연구
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• 제17권4호
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• pp.535-547
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• 2009

This study presented a making method of jeans pattern with high fitness after deriving the appropriate shrinkage rate by material and washing process. For this purpose of this study, 6 jeans have been tested after washing finishing and we turned out appropriate shrinkage rate by evaluating the exterior of jeans and usage satisfaction. Then, a making method of jeans pattern was presented after applying the optimized shrinkage rate. According to the result of the exterior evaluation of test jeans, all 6 jeans were rated high with scores close to 3.5. Following the evaluation of satisfaction of usage by physical movement, the highest ranking was in the order of walking with normal steps, back bending $90^{\circ}$, chair sitting, climbing stairs, and squatting. The shrinkage rate by physical area showed the highest score in the order of pants length, waist circumference, thigh circumference, knee circumference, hem circumference, hips circumference. In addition, the shrinkage rate was higher in warp direction than weft direction after washing finishing. As for the result of addition and reduction of pattern measurements by parts of jeans, waist circumference was 2.6${\sim}$5.2cm, hips circumference was 1.3${\sim}$4.2cm, thigh circumference was 0.8${\sim}$3.1cm and knee circumference was 0.7${\sim}$2.5cm. Also, hem circumference was 0.5${\sim}$1.8cm and pants length was 4.0${\sim}$6.2cm. That is, this results showed a wide range of addition and reduction according to material and washing finishing.

• Journal of Ceramic Processing Research
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• 제19권6호
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• pp.509-513
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• 2018

This study uses fly ash for non-shrinkage grout in order to develop strength of grout and improve its durability. We grind fly ash to the extent of $7,000cm^2/g$ and use ground fly ash and raw fly ash respectively at the proportion of 10%, 20%, 30% instead of OPC and compare the results drawn on the condition of each proportion. As a mixed material of grout, EVA and water-reducing agent is added in order to prevent bleeding and improve segregation resistance, CSA is added with a view to preventing drying shrinkage and improving early strength property. In regard to flow and flow time test for analyzing and evaluating workability, it is revealed that grouts of all mix proportions except raw fly ash 30% mix proportion satisfy all performance criteria. With regard to length change rate, grout with no admixture shows the highest shrinkage rate, but the rate is 0.0005%, extremely insignificant rate. As material age increases, compressive strength of two grouts, that is to say ground fly ash 10% and 20%-used grouts, exceed that of grout with no admixture or show high-level compressive strength.

• 한국세라믹학회지
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• 제35권3호
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• pp.273-279
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• 1998

Unite cell of soid oxide fuel cell (SOFC) that consists of a dense yttria-stabilized zirconia(YSZ) electrolyte a porous nickel-YSZ cermet anode and a porous strontium- doped lanthanum manganate(LSM) cathod was fabricated from using pore former through co-firing technique. Initial sintering shrinkage rates of each layer were identified for fabricating SOFC. Heterogenous sintering was very effective in tailoring shrinkage rate for three layers. The powder tailoring necessary for shrinkage rate matching are as follows ; electrolyte of 60% TZ8YS/ 40% TZ8Y mixture anode of 51wt% NiO/49 wt% (70wt% TZ8YS/30 wt% UT ZrO2) mixture and cathode of 80% LSM/20% UT ZrO2 mixture . The overall sintering shrinkage rate differences of three layers using these compositions were maintained in a few percent.