• 제목/요약/키워드: Linear shrinkage

검색결과 207건 처리시간 0.03초

Clinochlore를 이용한 Cordierite 소지의 생성 및 성질에 미치는 $Al_2$O$_3$의 영향 (The Effects of $Al_2$O $_2$ on the Formation and Properties of Cordierite Bodies with Clinochlore)

  • 안영필;황정길;최롱
    • 한국세라믹학회지
    • /
    • 제12권4호
    • /
    • pp.29-36
    • /
    • 1975
  • Korean clinochlore, kaolin, pyrophillite and a technical grade of alumina have been used to investigate the effects of Al2O3 on the formation and properties of cordierite bodies. The body compositions were formulated from the proper proportions of the above raw materials to cover the range of composition from the point corresponding to the stoichiometric formula of cordierite, bythe consecutive increasment of 0.2mol. Al2O3, toward the apex of Al2O3 on the MgO-Al2O3-SiO2 triaxial diagram. Each of bodies was fired with the elevated temperatures from 110$0^{\circ}C$ to 140$0^{\circ}C$ by 5$0^{\circ}C$ interval. Linear shrinkage and water absorption were taken as measures for the firing range of the bodies. The formation of cordierite was estimated from the comparative study of X-ray diffraction and dilatometry of the fired bodies. The formation of a large amount of cordierite was initiated about 120$0^{\circ}C$. The content of Al2O3 exceeded up to 0.8 mol. comparing to the stoichiometric formula of cordierite broadens the firing range of the body.

  • PDF

멜라민시트 적층 MDF 마루판재의 가열에 의한 치수변화 (Dimensional Change of Melamine Sheet Laminated MDF Flooring by Heating)

  • 민일홍;김의식;한규성
    • Journal of the Korean Wood Science and Technology
    • /
    • 제24권4호
    • /
    • pp.32-39
    • /
    • 1996
  • The overall purpose of this study was to investigate the dimensional changes of melamine sheet laminated medium density fiberboard(MDF) floorings by sub-heating system(Ondol). This study was also conducted to improve the properties of melamine sheet laminated MDF floorings. The effects of density, resin content, manufacturing speed of MDF and types of melamine sheet on dimensional and weight changes of floorings were investigated. The results were as followings. 1. Dimensional and weight change of melamine sheet laminated MDF flooring by heating decreased with decreasing the density of MDF. 2. Dimensional and weight change of melamine sheet laminated MDF flooring by heating decreased with increasing the resin content of MDF. 3. Dimensional and weight change of melamine sheet laminated MDF flooring by heating decreased with decreasing the manufacturing speed of MDF. 4. Dimensional change of melamine sheet laminated MDF flooring in width direction by heating was doubled than that in machine direction. 5. Dimensional change and curling of high pressure melamine laminate(HPM) laminated MDF flooring by heating was less than those of low pressure melamine laminate(LPL) flooring. 6. Weight loss of melamine sheet laminated MDF flooring by heating has linear relationship with shrinkage.

  • PDF

Effect of outliers on the variable selection by the regularized regression

  • Jeong, Junho;Kim, Choongrak
    • Communications for Statistical Applications and Methods
    • /
    • 제25권2호
    • /
    • pp.235-243
    • /
    • 2018
  • Many studies exist on the influence of one or few observations on estimators in a variety of statistical models under the "large n, small p" setup; however, diagnostic issues in the regression models have been rarely studied in a high dimensional setup. In the high dimensional data, the influence of observations is more serious because the sample size n is significantly less than the number variables p. Here, we investigate the influence of observations on the least absolute shrinkage and selection operator (LASSO) estimates, suggested by Tibshirani (Journal of the Royal Statistical Society, Series B, 73, 273-282, 1996), and the influence of observations on selected variables by the LASSO in the high dimensional setup. We also derived an analytic expression for the influence of the k observation on LASSO estimates in simple linear regression. Numerical studies based on artificial data and real data are done for illustration. Numerical results showed that the influence of observations on the LASSO estimates and the selected variables by the LASSO in the high dimensional setup is more severe than that in the usual "large n, small p" setup.

Synthesis of Lanthanides Doped $CaTiO_3$ Powder by the Combustion Process

  • Jung, Choong-Hwan;Park, Ji-Yeon;Lee, Min-Yong;Oh, Seok-Jin;Kim, Hwan-Young;Hong, Gye-Won
    • The Korean Journal of Ceramics
    • /
    • 제6권1호
    • /
    • pp.47-52
    • /
    • 2000
  • Lanthanides such as La, Gd and Ce have recognized as elements of high level radioactive wastes immobilized by forming solid solution with $CaTiO_3$. For easy forming solid solution between $CaTiO_3$and lanthanides, the combustion synthesis process was applied and the powder characteristics and sinterability were investigated. The proper selection of the type and the composition of fuels are important to get the crystalline solid solution of $CaTiO_3$and lanthanides. When glycine or the mixtures of urea and citric acid with stoichiometric composition was used as a fuel, the solid solution of $CaTiO_3$with $La_2O_3$or $Gd_2O_3$or $CeO_2$was produced very well by the combustion process. The combustion synthesized powder seemed to have a good sinterability with the linear shrinkage of more than 25% up to $1500^{\circ}C$, while that of the solid state reacted powder was less than 10% at the same condition.

  • PDF

반응 소결 Alumina의 소결거동과 기계적 성질에 미치는 Al 첨가량의 영향 (Effect of Al Amount on the Sintering Behavior and Mechanical Properties of Reaction Bonded Alumina)

  • 장복기;문종하;이종호
    • 한국세라믹학회지
    • /
    • 제34권5호
    • /
    • pp.519-527
    • /
    • 1997
  • The effect of Al content and heating rate on the sintering behavior, microstructure, and mechanical properties of reaction bonded alumina (RBAO) was investigated. As the heating rate became slower a critical Al content which could be added to RBAO increased. The weight gain and linear shrinkage of RBAO containing of 55 vol% Al were 28% and 6.5%, respectively. The relative density of RBAO decreased from 96 to 94%, as the amount of Al increased from 15 to 55 vol%. The hardness of RBAO increased from 17.8 to 19.9 GPa and the bending strength enhanced from 370 to 570 MPa, as the amount of Al increased from 15 to 55 vol%. On the other hand, the wear rate of RBAO degraded from 6.7 to 3.39$\times$10-5 $\textrm{mm}^2$/kg and the fracture toughness decreased from 4.1 to 3.6 MPa.m1/2, as the amount of Al increased from 15 to 55 vol%. Fracture modes were shown to the mixed mode of inter/transgranular. However, transgranular fracture was dominant with increasing the content of Al.

  • PDF

공침법에 의한 Cordierite분말의 합성 및 소결에 관한 연구 (Synthesis and Sintering of Cordierite by using Coprecipitation Method)

  • 한문희;박금철
    • 한국세라믹학회지
    • /
    • 제27권7호
    • /
    • pp.899-906
    • /
    • 1990
  • The cordierite powders were prepared from Mg(NO3)2.6H2O, Al(NO3)3.9H2O and colloidal silica by the coprecippitation method, and the sintering behavior of the powders were investigated. Two different methods were applied for producing the precursor powders. The one was to added the aqueous solution of Mg(NO3)2.6H2O and Al(NO3)3.9H2O to NH4OH to adjust pH at 10 where the colloidal silica of pH 10 was added. The other wa to add the aqueous solution of Mg(NO3)2.6H2O and Al(NO3)3.9H2O to the colloidal silica with NH4OH to control the final mixture to be at pH 10. It was confirmed that more homogeneous powders were obtained from the latter method. The firing linear shrinkage of the powder compacts fabricated from the calcined powder between 90$0^{\circ}C$ and 110$0^{\circ}C$ was found to be larger as the calcination temperature was low. But all of them stopped shrinking around 120$0^{\circ}C$. The powder compacts, fabricated using the calcined powders at 90$0^{\circ}C$ and 95$0^{\circ}C$ for 2hours and sintered at 142$0^{\circ}C$ for 2hours, showed relative density of 93-96%, 3-point bending strength of 81-83MPa, KIC of 1.9-2.4 MPam1/2 and thermal expansion coefficient of 0.213-0.732$\times$10-6$^{\circ}C$.

  • PDF

스크린 콘텐츠 비디오의 압축을 위한 인접 화소의 가중 합을 이용한 적응적 Residual DPCM 기법 (Adaptive Residual DPCM using Weighted Linear Combination of Adjacent Residues in Screen Content Video Coding)

  • 강제원
    • 방송공학회논문지
    • /
    • 제20권5호
    • /
    • pp.782-785
    • /
    • 2015
  • 그래픽스 등 컴퓨터로 합성한 영상을 일컫는 스크린 콘텐츠 비디오의 경우는 색대비가 높은 그래픽 요소로 인하여 예측 후에도 잔차 신호의 공간적 연관성이 여전히 높게 나타나므로 현 샘플의 가장 인접한 화소를 이용하는 residual differential pulse-code modulation (RDPCM) 기법을 효율적으로 적용할 수 있다. 본 논문에서는 잔차 신호의 주위 인접 화소의 가중 합으로 보다 정확한 예측의 RDPCM을 수행하는 부호화 기법을 제안한다. 각 가중 계수는 현재 잔차 신호의 인접 영역에서 왜곡 값에 L1 정규화를 포함한 비용함수를 최소화 하여 추정한다. 제안 기법은 스크린 콘텐츠 동영상 압축 참조 코덱 대비 약 3.1%의 부호화 성능 향상을 보인다.

수종의 화학소독제에 침적시킨 고무인상체의 크기안정성에 관한 연구 (A STUDY ON DIMENSIONAL STABILITY OF THE RUBBER IMPRESSION MATERIALS FOLLOWING IMMERSION WITH CHEMICAL DISINFECTANTS)

  • 김형식;김창회
    • 대한치과보철학회지
    • /
    • 제27권2호
    • /
    • pp.249-259
    • /
    • 1989
  • Dental impression materials often become contaminated with patients' saliva and blood which creates the potential for cross-infection. It was the purpose of this study to investigate the effects of disinfection of three different rubber impression materials with four different disinfecting solutions. Polysulfide, vinyl polysiloxane and polyether impression materials were mixed according to the manufacturer's directions and samples were formed on a stainless steel model. On removal from the standard model, impressions were immersed in a disinfectant (acid-potentiated glutaraldehyde, phenollic compound, chlorine compound, iodophor) at room tempera tures for ten minutes. After disinfection, the distance between reference points(linear dimension) was measured using the non-contact automatic cordinate measuring projector(MZ-1, Nikon). Through statistical analyses on the data from this study,. the following conclusions were obtained. 1. Polysulfide, vinyl polysiloxane impressions were disinfected without dimensional change.(p>0.05) 2. Polyether impressions which were immersed in acid-potentiated glutaraldehyde were statistically different from control group.(p<0.05) But the amount of shrinkage(0.04%) would not be clinically significant. 3. By immersion of polysulfide, vinyl polysiloxane, polyether impressions in Banicide, Biocide, Multicide plus, sodium hypochlorite for ten minutes, clinically accurate impressions were obtained without dimensional change.

  • PDF

알파반수석고 치환 고로슬래그 시멘트 모르타르의 경화특성 및 미세구조 분석 (Hardening Characteristics and Microstructure Analysis of Blast Furnace Slag-Cement Mortar Replaced Alpha-calcium Sulfate Hemihydrate)

  • 김경태;김규용;이보경;윤민호;이상규;서원우
    • 한국건축시공학회:학술대회논문집
    • /
    • 한국건축시공학회 2017년도 춘계 학술논문 발표대회
    • /
    • pp.18-19
    • /
    • 2017
  • In this study, hardening characteristics and microstructure of blast furnace slag-cement mortar replaced alpha-calcium sulfate hemihydrate were analyzed. As a result of replacing alpha-calcium sulfate hemihydrate with 0, 10, 20, 30%, it was confirmed that the initial and final setting times are faster than that of blast furnace slag-cement mortar. The compressive strength of the specimens containing alpha-calcium sulfate hemihydrate decreased in the range of 42 ~ 76% at age 28 days compared with blast furnace slag-cement mortar. In the case of replacing the alpha-calcium sulfate hemihydrate, the shrinkage did not occur more rapidly than the cement mortar, but the slope of the strain curve showed a linear behavior. The results of scanning electron microscopy images analysis showed that the formation of ettringite was increased at alpha-calcium sulfate hemihydrate replaced mortar.

  • PDF

On the Use of Adaptive Weights for the F-Norm Support Vector Machine

  • Bang, Sung-Wan;Jhun, Myoung-Shic
    • 응용통계연구
    • /
    • 제25권5호
    • /
    • pp.829-835
    • /
    • 2012
  • When the input features are generated by factors in a classification problem, it is more meaningful to identify important factors, rather than individual features. The $F_{\infty}$-norm support vector machine(SVM) has been developed to perform automatic factor selection in classification. However, the $F_{\infty}$-norm SVM may suffer from estimation inefficiency and model selection inconsistency because it applies the same amount of shrinkage to each factor without assessing its relative importance. To overcome such a limitation, we propose the adaptive $F_{\infty}$-norm ($AF_{\infty}$-norm) SVM, which penalizes the empirical hinge loss by the sum of the adaptively weighted factor-wise $L_{\infty}$-norm penalty. The $AF_{\infty}$-norm SVM computes the weights by the 2-norm SVM estimator and can be formulated as a linear programming(LP) problem which is similar to the one of the $F_{\infty}$-norm SVM. The simulation studies show that the proposed $AF_{\infty}$-norm SVM improves upon the $F_{\infty}$-norm SVM in terms of classification accuracy and factor selection performance.