• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.3
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• pp.219-223
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• 2009

This paper prescribed the structural integrity of the API 5L X65 pipeline subjected to tensile pre-strain. The effects of pre-strain on the mechanical properties of API 5L X65 pipe were substantially investigated through a variety of the experimental procedures. Axial tensile pre-strain of 1.5, 5 and 10% was applied to plate-type tensile specimens cut from the pipe body prior to mechanical testing. Tensile test revealed that yield strength and tensile strength were increased with increasing tensile pre-strain. The increasing rate of the yield strength owing to the pre-strain is greater than that of the tensile strength. However, the pre-strain up to 5% had a little effect on the decreasing of the fracture toughness. The structural integrity of the API 5L X65 pipeline subjected to large plastic deformation was evaluated through the fitness-for service code.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.7
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• pp.629-637
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• 2008

We report several experimental data capable of evaluating the amorphous-to-crystalline (a-c) phase transformation in $(Ag)_x(Ge_2Sb_2Te_5)_{1-x}$ (x = 0, 0.05, 0.1) thin films prepared by a thermal evaporation. The isothermal a-c structural phase changes were evaluated by XRD, and the optical transmittance was measured in the wavelength range of $800{\sim}3000$ nm using a UV-vis-IR spectrophotometer. A speed of the a-c transition was evaluated by detecting the reflection response signals using a nano-pulse scanner with 658 nm laser diode (power P = $1{\sim}17$ mW, pulse duration t = $10{\sim}460$ ns). The surface morphology and roughness of the films were imaged by AFM. It was found that the crystallization speed was so enhanced with an increase of Ag content. While the sheet resistance of c-phase $(Ag)_x(Ge_2Sb_2Te_5)_{1-x}$ was similar to that of c-phase $Ge_2Sb_2Te_5$ (i.e., $R_c{\sim}10{\Omega}/{\square}$), the sheet resistance of a-phase $(Ag)_x(Ge_2Sb_2Te_5)_{1-x}$ was found to be lager than that of a-phase $Ge_2Sb_2Te_5$, $R_a{\sim}5{\times}10^6{\Omega}{/\square}$. For example, the ratios of $R_a/R_c$ for $Ge_2Sb_2Te_5$ and $(Ag)_{0.1}(Ge_2Sb_2Te_5)_{0.9}$ were approximately $5{\times}10^5$ and $5{\times}10^6$, respectively.

• Bulletin of the Korean Mathematical Society
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• v.20 no.1
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• pp.45-49
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• 1983

If R is ring and M is a right (or left) R-module, then M is called a faithful R-module if, for some a in R, x.a=0 for all x.mem.M then a=0. In [4], R.E. Johnson defines that M is a prime module if every non-zero submodule of M is faithful. Let us define that M is of prime type provided that M is faithful if and only if every non-zero submodule is faithful. We call a right (left) ideal I of R is of prime type if R/I is of prime type as a R-module. This is equivalent to the condition that if xRy.subeq.I then either x.mem.I ro y.mem.I (see [5:3:1]). It is easy to see that in case R is a commutative ring then a right or left ideal of a prime type is just a prime ideal. We have defined in [5], that a chain of right ideals of prime type in a ring R is a finite strictly increasing sequence I$_{0}$.contnd.I$_{1}$.contnd....contnd.I$_{n}$; the length of the chain is n. By the right dimension of a ring R, which is denoted by dim, R, we mean the supremum of the length of all chains of right ideals of prime type in R. It is an integer .geq.0 or .inf.. The left dimension of R, which is denoted by dim$_{l}$ R is similarly defined. It was shown in [5], that dim$_{r}$R=0 if and only if dim$_{l}$ R=0 if and only if R modulo the prime radical is a strongly regular ring. By "a strongly regular ring", we mean that for every a in R there is x in R such that axa=a=a$^{2}$x. It was also shown that R is a simple ring if and only if every right ideal is of prime type if and only if every left ideal is of prime type. In case, R is a (right or left) primitive ring then dim$_{r}$R=n if and only if dim$_{l}$ R=n if and only if R.iden.D$_{n+1}$ , n+1 by n+1 matrix ring on a division ring D. in this paper, we establish the following results: (1) If R is prime ring and dim$_{r}$R=n then either R is a righe Ore domain such that every non-zero right ideal of a prime type contains a non-zero minimal prime ideal or the classical ring of ritght quotients is isomorphic to m*m matrix ring over a division ring where m.leq.n+1. (b) If R is prime ring and dim$_{r}$R=n then dim$_{l}$ R=n if dim$_{l}$ R=n if dim$_{l}$ R<.inf. (c) Let R be a principal right and left ideal domain. If dim$_{r}$R=1 then R is an unique factorization domain.TEX>R=1 then R is an unique factorization domain.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.726-729
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• 2000

Though L $a_{1+x}$S $r_{2-x}$M $n_2$ $O_{7}$ n=2 R-P phases have been well known to have CMR effect, it was generally believed that n=1 phase was insulating. But recently monolayered perovskite $Ca_{2-x}$L $n_{x}$Mn $O_4$phase has been reported to show magnetoresistance. In this study, layered perovskite $Ca_{2-x}$L $n_{x}$Mn $O_4$ (x=0, 0.5, Ln=Pr, Nd, Sm, Gd) phases were synthesized by solid state reaction and their structures were refined by Rietveld method. The space groups of $Ca_2$Mn $O_4$, N $d_{0.5}$C $a_{1.5}$Mn $O_4$phases were refined as C2cb and Fmmm, respectively.y.ely.y.y.y.y.y.y.

• Bulletin of the Korean Mathematical Society
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• v.53 no.5
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• pp.1385-1394
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• 2016

Let (R, m) be a Noetherian local ring, I, J two ideals of R, and A an Artinian R-module. Let $k{\geq}0$ be an integer and $r=Width_{>k}(I,A)$ the supremum of lengths of A-cosequences in dimension > k in I defined by Nhan-Hoang [9]. It is first shown that for each $t{\leq}r$ and each sequence $x_1,{\cdots},x_t$ which is an A-cosequence in dimension > k, the set $$\Large(\bigcup^{t}_{i=0}Att_R(0:_A(x_1^{n_1},{\ldots},x_i^{n_i})))_{{\geq}k}$$ is independent of the choice of $n_1,{\ldots},n_t$. Let r be the eventual value of $Width_{>k}(0:_AJ^n)$. Then our second result says that for each $t{\leq}r$ the set $\large(\bigcup\limits_{i=0}^{t}Att_R(Tor_i^R(R/I,\;(0:_AJ^n))))_{{\geq}k}$ is stable for large n.

• Journal of the Korean Mathematical Society
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• v.50 no.5
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• pp.973-989
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• 2013

We observe from known results that the set of nilpotent elements in Armendariz rings has an important role. The upper nilradical coincides with the prime radical in Armendariz rings. So it can be shown that the factor ring of an Armendariz ring over its prime radical is also Armendariz, with the help of Antoine's results for nil-Armendariz rings. We study the structure of rings with such property in Armendariz rings and introduce APR as a generalization. It is shown that APR is placed between Armendariz and nil-Armendariz. It is shown that an APR ring which is not Armendariz, can always be constructed from any Armendariz ring. It is also proved that a ring R is APR if and only if so is R[$x$], and that N(R[$x$]) = N(R)[$x$] when R is APR, where R[$x$] is the polynomial ring with an indeterminate $x$ over R and N(-) denotes the set of all nilpotent elements. Several kinds of APR rings are found or constructed in the precess related to ordinary ring constructions.

• Journal of the Korean Institute of Gas
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• v.15 no.6
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• pp.14-19
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• 2011

The objective of this study was to investigate the effect of the thickness eccentricity on the collapse pressure of a subsea pipeline subjected to external pressure. The collapse behavior of the subsea pipeline containing initial imperfection was evaluated using elastic-plastic finite element (FE) analyses. API 5L X65 and API 5L X80 Pipelines with the thickness eccentricity values between 4~16% were adopted to investigate the plastic collapse under hydrostatic pressure. A parametric study was shown that the plastic collapse pressure decreased when either the thickness eccentricity or the ratio of diameter to thickness increased.

• Journal of the Korean Mathematical Society
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• v.53 no.5
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• pp.1057-1075
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• 2016

Let R be a ring in which Nil(R) is a divided prime ideal of R. Then, for a suitable property X of integral domains, we can define a ${\phi}$-X-ring if R/Nil(R) is an X-domain. This device was introduced by Badawi [8] to study rings with zero divisors with a homomorphic image a particular type of domain. We use it to introduce and study a number of concepts such as ${\phi}$-Schreier rings, ${\phi}$-quasi-Schreier rings, ${\phi}$-almost-rings, ${\phi}$-almost-quasi-Schreier rings, ${\phi}$-GCD rings, ${\phi}$-generalized GCD rings and ${\phi}$-almost GCD rings as rings R with Nil(R) a divided prime ideal of R such that R/Nil(R) is a Schreier domain, quasi-Schreier domain, almost domain, almost-quasi-Schreier domain, GCD domain, generalized GCD domain and almost GCD domain, respectively. We study some generalizations of these concepts, in light of generalizations of these concepts in the domain case, as well. Here a domain D is pre-Schreier if for all $x,y,z{\in}D{\backslash}0$, x | yz in D implies that x = rs where r | y and s | z. An integrally closed pre-Schreier domain was initially called a Schreier domain by Cohn in [15] where it was shown that a GCD domain is a Schreier domain.

• Journal of agricultural medicine and community health
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• v.10 no.1
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• pp.42-48
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• 1985

This study was carried out to obtain the basic data for epdemiological survey of hypertension in old population (60 years or more). From May, 1983 to April, 1984, 365 males and 335 females who inhabit in Ko-Chang Gun, Chonbuk Province were investigated for several factors as their socio-econmic status and laboratory examinations with blood pressure, and which factors were analysed by simple correlation and multiple regression analysis. The results are summarized as follows; 1) Sample size of this study is equivalent to 5.2%(male;6.7%, female;4.3%) of population in 60 years or more age group, and the mean age of samples is 70.6${\pm}$5.3 (yr.) in males and 71.4${\pm}$5.3 (yr.) in female (P>0.05). 2) Mean blood pressure of males are 135.9${\pm}$21.3mm Hg in systolic and 85.3${\pm}$13.4mm Hg in diastolic phase and in female, 131.0${\pm}$23.6 mm Hg and 84.1${\pm}$19.9 mm Hg (P < 0.01). Their prevalence rates of hypertension (${\geq}$ 140 mm Hg in systolic, ${\geq}$ 95 mm Hg in diastolic phases) are 33.7% in males, 40.6% in females (P < 0.01). 3) Serum cholesterol levels and other independent variables are revealed in normal ranges, and except to Vervaeck index (89.4${\pm}$5.6 in males, 87.5${\pm}$6.7 in females, p<0.01), other are not significant sexual differences (P>0.05). 4) In the simple correlation analysis, the main factors that affect to blood pressure are serum cholesterol levels (P < 0.05) and Vervaeck index (P < 0.01) in males, age (P <0.05) and Vervaeck index (P <0.01) in females. 5) In multiple regression analysis, prediction equations for blood pressure are calculated as follows; Ysm=-64.55+0.161(X1)+0.124(X2)-0.047(X3)+1.953(X4) Ydm=18.61-0.125(X1)+0.060(X2)+0.032(X3)+0.720(X4) Ysf=-0.22+0.536(X1)+0.134(X2)+0.068(X3+0.788(X4) Yaf=-14.46+0.685(X1)+0.033(X2)+0.176(X3)+0.362(X4) Ysm : Systolic blood pressure in male, Ydm : Diastolic blood pressure in male, Ysf : Systolic blood pressure in female, Ydf : Diastolic blood pressure in female. X1 : Age(year), X2 : Serum cholesterol level (mg%), X3 : Fastin blood sugar (mg% ), X4 : Vervaeck index.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.3
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• pp.215-221
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• 1988

The hop yield prediction model developed based on meteorological elements in Hoeongseong was Y=6,042.846-17.665 $X_1$-0.919 $X_2$-96.538 $X_3$-138.105 $X_4$＋86.910 $X_{5}$ ＋ $X_{6}$ with MS $E_{p}$ of 25.258, $R_{p}$$^{2}$ of 0.9991, R $a_{p}$$^{2}$ of 0.9962 and $C_{p}$ of 7.00. The minimum air temperature at early growing stage ( $X_1$), the total precipitation at cone ripening stage ( $X_2$), the maximum air temperature at flower bud differentiation stage ( $X_3$) and the maximum air temperature at flowering stage ( $X_4$) influenced on hop yield as decrement weather elements. The average air temperature at early growing stage ( $X_{5}$ ) and the total sunshine hours at cone development stage ( $X_{6}$ ) influenced on hop yield as increment weather elements.lements.