• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.330-333
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• 2002

The stability against DC accelerated aging stress of $Dy_{2}O_{3}-doped$ $ZnO-Pr_{6}O_{11}-based$ varistor ceramics was investigated. The calculated nonlinear exponent$(\alpha)$ in varistor ceramics without $Dy_{2}O_{3}$ was only 4.9, whereas the $\alpha$ value of the varistors with $Dy_{2}O_{3}$ was abruptly increased in the range of 48.8 to 58.6. The varistor ceramics with $Dy_{2}O_{3}$ content of 1.0 mol% exhibited maximum ${\alpha}$, reaching 58.6, whereas they exhibited very poor stability. While, The varistor ceramics doped with 0.5 mol% $Dy_{2}O_{3}$ exhibited not only the high nonlinearity, which the ${\alpha}$ is 55.3 and the leakage current is $0.1{\mu}A$， but also the highest stability, which the variation rates of varistor voltage and nonlinear exponent are -0.8% and -14.3%, respectively, under DC accelerated aging stress, $0.95 V_{1mA}/150^{\circ}C/24h$.

• 산업경영시스템학회지
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• 제22권52호
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• pp.337-345
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• 1999

The long-tailed, positively skewed exponential distribution can be made into an almost symmetric distribution by taking the exponent of the data. In these situations, to use the traditional shewhart control limits on an individuals chart would be impractical and inconvenient. The transformed data, approximately bell-shaped, can be plotted conveniently on the individuals chart and exponentially weighted moving average chart. In this paper, using modifying statistics with transformed exponential of the data, we give a method for constructing control charts. Selecting method of exponent for individual chart is evaluated. And consider that smaller weight being assigned to the older data as time process and properties and taking method of exponent($\theta$), weighting factor($\alpha$) are suggested. Our recommendation, on the basis result of simulation, is practical method for EWMA chart.

• 대한수학회보
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• 제51권4호
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• pp.923-931
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• 2014

Let x be an element of a group G and be an automorphism of G. Then for a positive integer n, the autocommutator $[x,_n{\alpha}]$ is defined inductively by $[x,{\alpha}]=x^{-1}x^{\alpha}=x^{-1}{\alpha}(x)$ and $[x,_{n+1}{\alpha}]=[[x,_n{\alpha}],{\alpha}]$. We call the group G to be n-auto-Engel if $[x,_n{\alpha}]=[{\alpha},_nx]=1$ for all $x{\in}G$ and every ${\alpha}{\in}Aut(G)$, where $[{\alpha},x]=[x,{\alpha}]^{-1}$. Also, for any integer $n{\neq}0$, 1, a group G is called an n-auto-Bell group when $[x^n,{\alpha}]=[x,{\alpha}^n]$ for every $x{\in}G$ and each ${\alpha}{\in}Aut(G)$. In this paper, we investigate the properties of such groups and show that if G is an n-auto-Bell group, then the factor group $G/L_3(G)$ has finite exponent dividing 2n(n-1), where $L_3(G)$ is the third term of the upper autocentral series of G. Also, we give some examples and results about n-auto-Bell abelian groups.

• 한국안전학회지
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• 제7권1호
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• pp.20-29
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• 1992

Effects of strain hardening exponents on the retardation behavior of fatigue crack propagation are experimentally investigated. The retardation of fatigue crack propagation seems to be induced by the crack closure at crack tip. The phenomenon of crack closure becomes remarkable with the increment of strain hardening exponent and magnitude of percent peak load. The ratio of crack growth increment(a$\_$d//w$\_$d/) is influenced by a single overloading (a$\_$d/) and estimated plastic zone size (W$\_$d/=2r$\_$y/) is increased according with the increasing of strain ha.dening exponents. The number of retarded crack growth cycles were (N$\_$d/) decreased as the baseline stress intensity factor .ange( K$\_$b/) was increased. Within the limitation of these experimental results obtained under the single overload, an empirical relation between crack retardation ratio (Nd/N＊), strain hardening exponent (n) and percent peak load (％PL) has been proposed as; Nd/N＊＝ exp [PL $.$ PL$.$A(n)＋B(n) ] where, A(n)＝${\alpha}$n＋${\beta}$, B(n)＝${\gamma}$n＋$\delta$, PL＝％PL/100 and ${\alpha}$＝0.78, ${\beta}$＝0.54, ${\gamma}$＝0.58 and $\delta$＝-0.01, It is interesting to note that all these constants are identical for materials such as aluminum(A3203), steel(S4SC), steel(SS41) and stainless steel(SUS316) used in this experimental study.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.344-347
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• 2003

The varistor properties of the ZPCCT-based ceramics, which are composed of Zn-Pr-Co-Cr-Tb oxides, were investigated with $Tb_4O_7$ content in the range of $0.0{\sim}1.0\;mol%$. As $Tb_4O_7$ content is increased, the ZPCCT-based ceramics exhibited very high densification based on increasing density in the range of $5.73{\sim}5.84\;g/cm^3$. The varitor voltage($V_{1mA}$) and nonlinear exponent($\alpha$) was increased in the range of 280.9 to 751.8 and 29.8 to 44.4 with increasing $Tb_4O_7$ content, respectively. In particular, the maximum $\alpha$ of 44.4 was obtained from 1.0 mol% $Tb_4O_7$ and the, minimum leakage current($I_{\ell}$) of $1.0\;{\mu}A$ was obtained from 0.5 mol% $Tb_4O_7$.

• 한국전기전자재료학회논문지
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• 제15권9호
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• pp.776-782
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• 2002

The microstructure, V-Ι characteristics, and stability of ZnO-P $r_{6}$ $O_{11}$ CoO-C $r_2$ $O_3$- $Y_2$ $O_3$-based varistor ceramics were investigated with cooling rate in the range of 2~8$^{\circ}C$/min. The cooling rate relatively weakly affected the microstructure, the varistor voltage, and the leakage current in the V-Ι characteristics. But the nonlinear exponent relatively strongly affected by cooling rate. The cooling rate also greatly affected the stability of V-Ιand dielectric characteristics for DC accelerated aging stress. On the whole, the varistors cooled with 4$^{\circ}C$/fin exhibited the highest performance in the densification, nonlinearity, and stability. Especially, they exhibited a high stability, in which the variation rate of the varistor voltage( $V_{1㎃}$), the nonlinear exponent($\alpha$), and the dissipation factor(tan $\delta$) is -1.4%, -4.9%, and ＋60.0%, respectively, under DC accelerated aging stress such as 0.95 $V_{1㎃}$15$0^{\circ}C$/12 h)

• 대한수학회보
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• 제59권6호
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• pp.1471-1493
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• 2022

The goal of this paper is to establish the boundedness of bilinear Calderón-Zygmund operator BT and its commutator [b₁, b₂, BT] which is generated by b₁, b₂ ∈ BMO(ℝⁿ) (or ${\dot{\Lambda}}_{\alpha}$(ℝⁿ)) and the BT on generalized variable exponent Morrey spaces 𝓛^p(·),𝜑(ℝⁿ). Under assumption that the functions 𝜑₁ and 𝜑₂ satisfy certain conditions, the authors proved that the BT is bounded from product of spaces 𝓛^{p₁(·),𝜑₁}(ℝⁿ)×𝓛^{p₂(·),𝜑₂}(ℝⁿ) into space 𝓛^p(·),𝜑(ℝⁿ). Furthermore, the boundedness of commutator [b₁, b₂, BT] on spaces L^p(·)(ℝⁿ) and on spaces 𝓛^p(·),𝜑(ℝⁿ) is also established.

• 한국식품영양과학회지
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• 제32권8호
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• pp.1262-1269
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• 2003

효소류의 떡 노화에 미치는 영향을 검토하였다. DSC 열특성의 검토에서 호화개시온도는 GP(glucoamylase+pullulanase)로 처리한 경우가 71.1$^{\circ}C$로 가장 낮고 그 다음이 $\beta$-amylase, $\alpha$-amylase 순이었다. 또 호화최대온도는 효소 처리한 것이 대조구에 비해서 대부분 낮은 편이었으며 그 중 GP처리한 것이 가장 낮은 것으로 나타났다. 또 떡의 용융 enthalpy는 GP, $\beta$-amylase, $\alpha$-amylase 순으로 증가하였으며 GP의 용융 enthalpy값이 다른 경우보다 많이 낮게 나타났다. 재결정도는 GP의 값이 크게 낮은 것으로 나타났다. Avrami exponent(n)는 0.90 ∼ 1.20 범위에 있었으며 노화속도의 시간상수 1/k은 GP, $\beta$-amylase, $\alpha$-amylase, Control의 순이었다. 효소류를 첨가한 떡의 조직감은 대조구에 비해서 차이를 보였으며 종류별 효과는 GP, $\beta$-, $\alpha$-amylase의 순으로 나타났다. L＊ 값은 $\beta$-amylase를 제외하고는 모두 감소하고 a＊ 값은 효소간 5% 수준에서 유의차를 나타내었다. b＊ 값의 경우는 GP는 청색 방향으로, $\beta$-, $\alpha$-amylase는 반대인 황색 방향으로 변하였다. 효소 처리한 떡의 관능검사는 효소 처리한 것이 대조구보다 다소 높은 값을 나타내어 좋은 관능성을 보여주었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.705-709
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• 2003

The microstructure and electrical properties of the $Pr_6O_{11}$-based ZnO varistor ceramics, which are composed of Zn-Pr-Co-Cr-Tb oxides, were investigated with $Tb_4O_7$ amount. The varistor ceramics exhibited very high densification based on increasing density in the range of $5.73{\sim}5.85g/cm^3$ as $Tb_4O_7$ amount is increased. The calculated nonlinear exponent( ${\alpha}$ ) in varistor ceramics without $Tb_4O_7$ was only 8.9, whereas the ${\alpha}$ value of the varistor ceramics with $Tb_4O_7$ was abruptly increased in the range of 18.6 to 42.0. In particular, the maximum value(42.0) of ${\alpha}$ was obtained by doping of 1.0 mol% $Tb_4O_7$. The measured leakage current($I_{\ell}$) in varistor ceramics without $Tb_4O_7$ was $40.1{\mu}A$, whereas the $I{\ell}$ value of the varistors with $Tb_4O_7$ was very abruptly decreased below $5{\mu}A$. It is estimated that $Tb_4O_7$ additives will is applied usefully in development of varistors possessing high performance.

• 대한수학회지
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• 제38권1호
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• pp.101-123
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• 2001

For a linear operator Q from R(sup)d into R(sup)d and 0$\alpha$ and parameter b on the other. characterization of strictly (Q,b)-semi-stable distributions among (Q,b)-semi-stable distributions is made. Existence of (Q,b)-semi-stable distributions which are not translation of strictly (Q,b)-semi-stable distribution is discussed.