• 대한기계학회논문집A
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• 제40권9호
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• pp.767-773
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• 2016

산 및 알칼리 용액 속에 침지한 SiC 세라믹의 기계적 특성은 와이블 통계로 해석하였다. 시험편은 1373K에서 열처리를 행하였다. SiC의 부식은 KSL1607 방법에 의한 산 및 알칼리 용액 속에서 수행하였다. 부식된 균열치유재의 굽힘 강도는 부식되지 않은 균열치유재의 굽힘강도보다 산 및 알칼리 용액 속에서 각각 47% 및 70% 감소하였다. SiC 세라믹의 부식은 산 용액 속에서보다 알칼리 용액 속에서 더 빨랐다. 척도 파라미터 및 형상 파라미터는 모재와 부식재에서 평가하였다. 산 및 알칼리 용액에서 부식된 모재의 형상 파라미터는 산용액에서 크게 나타났다. 그러나 열처리재는 산용액에서 크게, 알칼리 용액에서 작게 나타났다. 모재 및 열처리재의 척도 파라미터는 산 및 알칼리 용액에서 모두 작게 나타났다.

• 한국전기전자재료학회논문지
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• 제23권3호
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• pp.216-221
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• 2010

Employing statistical design of experiments, the difference in doping behaviors of rare-earth ions and their effects on the dielectric property and microstructure of $BaTiO_3$-MgO-$MnO_2$-($Ba_{0.4}Ca_{0.6}$) $SiO_3-Re_2O_3$ (Re = $Y_2O_3$, $Er_2O_3$) system were investigated. Through the statistical analysis we have found that the amount of $Re_2O_3$ are significantly affecting on the dielectric properties. The $Re_2O_3$ improved the dielectric constant, dielectric loss and R*C constant, so the appropriate contents of $Y_2O_3$ and $Er_2O_3$ were 0.8 ~ 1.2 mol% and 0.8 ~ 1.3 mol%, respectively. The MLCC(mutilayer chip capacitor) with $2.0{\times}1.2{\times}1.2mm$ size and 475 nF was also suited for X7R with the above composition. It showed that the dielectric constant and RC constant were 2,839 and 3,675 ${\Omega}F$, respectively in the sintering condition at $1250^{\circ}C$ in $Po_2$ $10^{-7}$ Mpa.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.719-724
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• 2001

The study on reducing vehicle noise and vibration has gained much attention to ensure the comfortability as well as the safety. These days. in this paper, we applied Statistical Energy Analysis(SEA) to characterize the tire assembly, which is useful analytical tool for mid- and high-frequency range. First, the SEA tire model was developed by dividing the tire and the wheel into several subsystems. The material properties were estimated experimentally. Finally. the SEA model was validated by comparing the estimated and the measured. In addition, we investigated the energy level and the energy transfering paths through the tire assembly in different frequency region.

• 콘크리트학회논문집
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• 제26권3호
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• pp.343-350
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• 2014

이 연구에서 몬테카를로 시뮬레이션을 이용해 확률론적 시공단계해석을 수행한 이유는 재료 특성, 환경 요인 및 하중에 대한 불확실성의 영향을 고려하기 위해서이다. 지금까지의 연구에서는 크리프 및 건조수축이 완전히 독립적인 확률 변수라고 가정되었다. 그러나 크리프 및 건조수축 추정을 위한 재료모델의 공통적인 영향요인 때문에 크리프 및 건조수축 사이에 강한 상관관계를 추정 할 수 있다. 이 논문에서는 CEB-FIB모델의 크리프 및 건조수축식을 이용하여 몬테카를로 시뮬레이션을 수행하여 실제 두 현상 사이의 상관 계수를 평가 한 후 재료 특성, 환경 요인 및 하중의 확률 변수의 영향을 받는 축방향 변형의 통계적 특성을 평가하기위해 몬테카를로 시뮬레이션을 한번 더 사용하였다. 몬테카를로 시뮬레이션의 결과는 58층 건물의 첫 번째 층의 기둥의 변형률과 비교 했다. 비교 결과는 재료특성에 불확실성에 의한 변화가 가장 큰 것으로 나타났다. 측정된 변형률은 평균+표준 편차 범위 안에 있었다.

• 한국건축시공학회지
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• 제2권4호
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• pp.89-98
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• 2002

Self-leveling material(SLM) is one of the floor finishing materials which make flat surface like as water level by itself in a short time. So it is possible to increase construction speed and enhance economical efficiency In this study, author intended to develop SLM for the industrial warehouse and factory loading heavy weight machinery and vehicles. The demanded properties for this type of SLM are above 200mm of flow value and above 300kgf/$cm^2$ of 28-days compressive strength. To possess demended strength and fluidity, SLM have to be composed of many types of binders and chemical additives. So it is difficult to decide suitable mixing proportion of composition materials. In this study, author investigated the weight percentage effect of main composition materials for high-strength self-leveling material, by experimental design such as tables of orthogonal arrays and simplex design, and by statistical analysis such as analysis of variance and analysis of response surface. Variables of experiments were ordinary Portland cement(OPC), alumina cement(AC), anhydrous gypsum(AG), lime stone(LS) and sand, and properties of tests were fluidity of fresh state and strength of hardened state. Results of this study are showed that suitable mix proportions of binders for the high strength self-leveling materials are two groups. One is 78~85.5% OPC, 7.5~9.5% AC, 9~12.5% AG and the other is 72.5~78% OPC, 9~12.5% AC, 13~15% AG.

• 동력기계공학회지
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• 제17권4호
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• pp.86-93
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• 2013

This paper deals with the effects of driving force and material properties on statistical distribution of fatigue crack growth rate (FCGR) for the friction stir welded joints of Al 7075-T651 aluminum plate. In this work, the statistical probability distribution of fatigue crack growth rate was analyzed by using our previous constant stress intensity factor range controlled fatigue crack growth test data. As far as this study are concerned, the statistical probability distribution of fatigue crack growth rate for the friction stir welded (FSWed) joints was found to evaluate the variability of fatigue crack growth rate for base metal (BM), heat affected zone (HAZ) and weld metal (WM) specimens. The probability distribution of fatigue crack growth rate for FSWed joints was found to follow well log-normal distribution. The shape parameter of BM and HAZ was decreased with increasing the driving force, however, the shape parameter of WM was decreased and increased with increasing the driving force. The scale parameter of BM, HAZ and WM was increased with the driving force.

• 한국치위생학회지
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• 제1권2호
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• pp.171-180
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• 2001

The purpose of this study was to compared with the properties of commercial polyvinyl siloxane impression materials on the Korean product and the other country one. The materials used in this study were 5 hydrophilic polvinyly siloxane impression materials of light body automixing type (Perfect-F, Handae Chemical, Korea; Examix, GC, Japan; Contrast, VOCO, Germany; Express, 3M, U.S.A; Extrude, Kerr, U.S.A.). Specimens of each impression material were fabricated from a mold with dimensions identical to that specified in ASTM D624-91 and were subjected to tensile lode at 500 mm/min until failure for tear strength. Properties of consistency, strain in compression, recovery from deformation, detail reproduction and linear dimensional change were tested according to the testing methods of the ISO specification no.4823(1992). From this study, the follow ing results were obtained 1. The tear strength values were high ET(3.4kN/m), EP(3.4kN/m), PF(3.0kN/m), CT(3.0kN/m), but the lowest was EM(2.2kN/m)(p<0.05). 2. In the consistency, CT(47 mm) had the highest value, followed by PF(42.1 mm), ET(41.2 mm), and EM(39.6 mm), EP(39.2 mm)(p<0.05). It means more flow that the consistency value is high. 3. The strain in compression values were high followed by EM(5.8%), PF(52%), CT(4.6%), ET(4.1%), EP(2.9%)(p<0.05). 4. In the recovery from deformation, ET(99.95%) and PF(99.90%) had the highest value, followed by EP(99.75%), EM(99.74%) without statistical signification, CT(99.64%) had the lowest value(p<0.05). 5. Detail reproduction reappeared to line $20{\mu}m$ all products. 6. The linear dimensional change was a little shrinked all products. and there were not statistical signification (p>0.05). All products were satisfied the ISO specification.

• Transactions on Electrical and Electronic Materials
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• 제16권5호
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• pp.260-263
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• 2015

Epoxy/micro-sized alumina composite was prepared and the effects of alumina content on the electrical and mechanical properties were investigated in order to develop an insulation material for gas insulated switchgear (GIS). Nano-sized alumina (average particle size: 30 μm) was also incorporated into the epoxy/micro-sized alumina composite. An electrical insulation breakdown strength test was carried out in sphere-sphere electrodes and the data were estimated by Weibull statistical analysis. Tensile strength was measured at a crosshead speed of 10 mm/min using a universal testing machine. Alumina content was varied from 0 wt% to 70 wt%.). As micro-sized alumina content increased, insulation breakdown strength increased until 40 wt% alumina content and decreased after that content. The tensile strength of a neat epoxy system was 82.2 MPa and that value for 60 wt% alumina content was 91.8 MPa, which was 111.7% higher than inthe neat epoxy system. The insulation breakdown strength of micro-sized alumina (60 wt%)/nano-sized alumina (1 phr) glycerol diglycidyl ether (GDE) (1 phr) composite was 54.2 MPa, which was 116% higher than the strength of the system without nano-sized alumina.

• Structural Engineering and Mechanics
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• 제46권1호
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• pp.53-73
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• 2013

Prediction of prestressed concrete girder integral abutment bridge (IAB) load effect requires understanding of the inherent uncertainties as it relates to thermal loading, time-dependent effects, bridge material properties and soil properties. In addition, complex inelastic and hysteretic behavior must be considered over an extended, 75-year bridge life. The present study establishes IAB displacement and internal force statistics based on available material property and soil property statistical models and Monte Carlo simulations. Numerical models within the simulation were developed to evaluate the 75-year bridge displacements and internal forces based on 2D numerical models that were calibrated against four field monitored IABs. The considered input uncertainties include both resistance and load variables. Material variables are: (1) concrete elastic modulus; (2) backfill stiffness; and (3) lateral pile soil stiffness. Thermal, time dependent, and soil loading variables are: (1) superstructure temperature fluctuation; (2) superstructure concrete thermal expansion coefficient; (3) superstructure temperature gradient; (4) concrete creep and shrinkage; (5) bridge construction timeline; and (6) backfill pressure on backwall and abutment. IAB displacement and internal force statistics were established for: (1) bridge axial force; (2) bridge bending moment; (3) pile lateral force; (4) pile moment; (5) pile head/abutment displacement; (6) compressive stress at the top fiber at the mid-span of the exterior span; and (7) tensile stress at the bottom fiber at the mid-span of the exterior span. These established IAB displacement and internal force statistics provide a basis for future reliability-based design criteria development.

• 복식문화연구
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• 제14권1호
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• pp.64-78
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• 2006

The purpose of this study is to set a characteristic design by analyzing formative properties for the hat and fashion image shown in fashion collections from the S/S season of 1998 to the F/W season of 2004 in recent seven years. For the study, the 96 stimuli which found frequently in fashion collection were selected. The examines for the image evaluation were women college students majoring fashion design related fields and living in Seoul, Gyeonggi-do, and Gyeongsangnam-do. Data collection was performed in August 2004. As statistical methods for data analysis, internal consistency method, Factor Analysis, MANOVA were used. Based on the analysis of 31 pairs of adjectives for elucidating the total 96 stimuli which were devised by altering the types of garment, the relation between a garment and a color of hat, the types of hat, the length of hair, and the material and design of garment, five factors or attractiveness, gracefulness, concentration, cuteness, and hardness and softness were deduced. And it showed much difference in the types of garment, the relations between a garment and a color of hat, the types of hat, the length of hair, and the material and design of a garment.