• Steel and Composite Structures
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• 제45권3호
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• pp.305-330
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• 2022

This article aims to investigate the static deflection and stress analysis of bi-directional functionally graded porous plate (BDFGPP) modeled by unified higher order kinematic theories to include the shear stress effects, which not be considered before. Different shear functions are described according to higher order models that satisfy the zero-shear influence at the top and bottom surfaces, and hence refrain from the need of shear correction factor. The material properties are graded through two spatial directions (i.e., thickness and length directions) according to the power law distribution. The porosities and voids inside the material constituent are described by different cosine functions. Hamilton's principle is implemented to derive the governing equilibrium equation of bi-directional FG porous plate structures. An efficient numerical differential integral quadrature method (DIQM) is exploited to solve the coupled variable coefficients partial differential equations of equilibrium. Problem validation and verification have been proven with previous prestigious work. Numerical results are illustrated to present the significant impacts of kinematic shear relations, gradation indices through thickness and length, porosity type, and boundary conditions on the static deflection and stress distribution of BDFGP plate. The proposed model is efficient in design and analysis of many applications used in nuclear, mechanical, aerospace, naval, dental, and medical fields.

• 한국자동차공학회논문집
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• 제10권6호
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• pp.72-79
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• 2002

The main objective of this study is to investigate the relationship between chemical structure and higher heating value of reformed diesel fuels by ultrasonic irradiation. In order to analyze the chemical structure changes of the reformed diesel fuels by ultrasonic irradiation, Proton nuclear magnetic resonance spectrometer(1H-NMR) was used and to analyze the effect of higher heating values of these diesel fuels, the bomb calorimeter was used. From the study, following conclusive remarks can be made. 1) The aromatic carbon percentages and higher heating values of the reformed diesel fuels by ultrasonic irradiation increased more than the conventional diesel ones. 2) The aromatics percentages and Branch Index(BI) of the reformed diesel fuels by ultrasonic irradiation decreased more than the conventional diesel ones. 3) The higher heating values on both for conventional fuel and reformed diesel fuels by ultrasonic energy irradiation is directly proportional to aromatic carbon percentages and inversely proportional to aromatic percentages and BI for these fuels.

• 산업기술연구
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• 제18권
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• pp.195-202
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• 1998

The effect of the number of nodes on the heat loss from a rectangular fin for a finite difference method is studied. There are two ways for selecting nodes for the upper half fin in this finite difference method. In the first place, all the ${\Delta}x$ are the same and all the ${\Delta}y$ are the same for the entire upper half fin. Incremental length of x (i.e. ${\Delta}x$) is divided by two near the fin tip while all the ${\Delta}y$ are the same for another way. The results show that 1) About 30 nodes are enough to obtain the satisfactory exact analysis (relative error < 5%) on the heat loss for a given range of Biot number in case of short fin (i.e. $L{\leq}2$). 2) Under usual circumstances (Bi<0.1), the relative error of heat loss between using 30 nodes and 90 nodes is within 4% for given range of non-dimensional fin length. 3) The relative error of the calculated heat loss (the number of node=90) as compared to the expected exact heat loss is less then 1.5% for Bi=0.1 and L=10 while that is over 13% for Bi=1.0 and L=10.

• 한국세라믹학회지
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• 제47권1호
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• pp.19-25
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• 2010

Traditional Kr$\ddot{o}$ger-Vink (K-V) notation defines sites in ionic crystals as interstitial or belonging to host ions. It enables description and calculations of combinations of native and foreign defects, including dopants and substituents. However, some materials exhibit inherently disordered partial occupancy of ions and vacancies, or partial occupancy of two types of ions. For instance, the high temperature disordered phases of $Bi_2O_3$, $Ba_2In_2O_5$, $La_2Mo_2O_9$, mayenite $Ca_{12}Al_{14}O_{33}$, AgI, and $CsHSO_4$ are all good ionic conductors and thus obviously contain charged point defects. But traditional K-V notation cannot account for a charge compensating defect in each case, without resorting to terms like "100% substitution" or "Frenkel disorder". the former arbitrary and awkward and the latter inappropriate. Instead, a K-V compatible nomenclature in which the partially occupied site is defined as the perfect site, has been proposed. I here introduce it thoroughly and provide a number of examples.

• 대한수학회논문집
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• 제23권3호
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• pp.371-376
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• 2008

In this paper, it is shown that if f satisfies the following functional inequality (0.1) $${\parallel}\sum\limits_{i,j=1}^3\;f{(xi,yj)}{\parallel}{\leq}{\parallel}f(x_1+x_2+x_3,\;y_1+y_2+y_3){\parallel}$$ then f is a bi-additive mapping. We moreover prove that if f satisfies the following functional inequality (0.2) $${\parallel}2\sum\limits_{j=1}^3\;f{(x_j,\;z)}+2\sum\limits_{j=1}^3\;f{(x_j,\;w)-f(\sum\limits_{j=1}^3\;xj,\;z-w)}{\parallel}{\leq}f(\sum\limits_{j=1}^3\;xj,\;z+w){\parallel}$$ then f is an additive-quadratic mapping.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2002년도 추계기술심포지움논문집
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• pp.69-72
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• 2002

B $i_{3.3}$L $a_{0.7}$ $Ti_3$ $O_{12}$(BLT) 강유전체 박막을 $Al_2$ $O_3$/Si 기판위에 졸-겔(sol-gel)법으로 스핀 코팅하여 Metal-Ferroelectric-Insulator-Silicon (MFIS) 구조를 형성하였다. 박막의 결정화를 위해 as-coated 박막을 산소분위기에서 $650^{\circ}C$ 및 $700^{\circ}C$에서 30분 동안 후속열처리를 실시하였다. BLT 박막의 열처리 온도를 $650^{\circ}C$에서 $700^{\circ}C$로 증가시킴에 따라서 c축으로 우선 배향되는 경향을 보였으며, FWHM 값이 감소하여 결정성이 향상됨을 확인할 수 있었다. $700^{\circ}C$에서 열처리된 BLT 박막의 memory window는 약 2.5V (인가전압 5V)를 나타내었으며, 누설전류는 약 1.5x$10^{-7}$ A/$\textrm{cm}^2$를 나타내었다.다.다.

• Bulletin of the Korean Chemical Society
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• 제24권7호
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• pp.885-886
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• 2003

• 한국초전도ㆍ저온공학회논문지
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• 제7권3호
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• pp.29-33
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• 2005

Critical current$(I_c)$ degradation of High $T_c$ Superconducting(HTS) tapes and AC loss under mechanical load is one of the hottest issues in HTS development and application. Mechanical load reduces the critical current of superconducting wire, and the $I_c$ degradation affects the AC loss of the wire. We measured the $I_c$ degradation and AC loss under tension and bending of Bi-2223 tapes made by 'Powder-in-Tube' technique at 77K with self-field. Also, we have studied the frequency characteristics on self-field AC loss in multi-filamentary Bi-2223/Ag tape at 77K. The measurement results and discussions on the relationship between $I_c$ degradation and AC loss are presented.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2006년도 추계학술대회 발표 논문집
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• pp.166-169
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• 2006

A promising capacitor, which has conformable step coverage and good uniformity of thickness and composition, is needed to manufacture high-density non-volatile FeRAM capacitors with a stacked cell structure. In this study, ferroelectric $Bi_{3.61}Nd_{0.39}Ti_3O_{12}$ (BNT) thin films were prepared on $Pt(111)/Ti/SiO_2/Si$ substrates by the liquid delivery system MOCVD method. In these experiments, $Bi(ph)_3$, $Nd(TMHD)_3$ and $Ti(O^iPr)_2(TMHD)_2$ were used as the precursors and were dissolved in n-butyl acetate. The BNT thin films were deposited at a substrate temperature and reactor pressure of approximately $600^{\circ}C$ and 4.8 Torr, respectively. The microstructure of the layered perovskite phase was observed by XRD and SEM. The remanent polarization value (2Pr) of the BNT thin film was $31.67\;{\mu}C/cm^2$ at an applied voltage of 5 V.

• 한국추진공학회지
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• 제3권3호
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• pp.16-24
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• 1999

다른 윗면 경사각을 가진 사다리꼴 휜 들에 대한 성능 해석이 3차원 해석적 방법에 의하여 조사된다. 단지 경사요소 값을 조정함으로써 한가지 식으로 다른 경사각을 가진 사다리꼴 횐 들을 해석할 수 있는 것이 보여진다. 나머지 변수들을 임의로 고정하였을 때 휜들의 성능들이 무차원 휜 길이, 휜 폭, Biot 수 그리고 경사요소에 대한 함수로 보여진다. 하나의 결과로서 Biot 수가 0.1 이하의 경우에서는 Biot 수, 무차원 휜 폭 그리고 경사요소가 감소함에 따라, 반면에 무차원 길이가 증가함에 따라 휜 유용도는 증가 하나 더 큰 Biot 수에서는(즉, Bi=0.3) 유용도에 대한 횐 형상의 효과의 변화 경향은 다소간 불규칙적이다.