• 대한기계학회논문집A
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• 제27권6호
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• pp.923-929
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• 2003

In this paper, an analysis of fatigue crack growth behavior from a statistical point of view has been carried out. Fatigue crack growth tests were conducted on sixteen pre-cracked compact tension (CT) specimens of the pressure vessel (SPV50) steel in controlled identical load and environmental conditions. The assessment of the statistical distribution of fatigue crack growth experimental data obtained from SPV50 steel was studied and also the correlation of the parameter C and m in the Paris-Erdogan law was discussed. The probability distribution function of fatigue crack growth life seems to follow the 3-parameter Weibull. The fatigue crack growth rate seems to follow the 3-parameter Weibull and the log-normal distribution. The coefficient of variation (COV) of fatigue crack growth life was observed to decrease as the crack grows. Fatigue crack growth rate data shows a normal distribution for both m and logC. A strong negative linear correlation exists between the coefficient C and the exponent m.

• 한국신뢰성학회지:신뢰성응용연구
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• 제14권1호
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• pp.45-51
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• 2014

Thermal shock tests at two stress levels were performed to see the life (cycles) of LPF ASSY (low pass filter assembly) at normal stress level. In this case Coffin-Manson relationship is generally used to describe the relationship between the temperature difference and the life, together with the Weibull distribution describing the life at each stress level. So for given data Coffin-Manson is fitted to predict the life at normal stress level. However, different types of models are appropriate for this type of test. Hence, a more appropriate model such as General log-linear model which can also incorporate the duration at the highest and lowest temperatures and acceleration time will be introduced.

• Structural Engineering and Mechanics
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• 제60권1호
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• pp.71-90
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• 2016

In this paper, the normalized variable V=(log N-B)(log ${\Delta}{\sigma}-C$-C), as derived from the probabilistic S-N field of Castillo and Canteli, is taken as a reference for calculation of damage accumulation and probability of failure using the Miner number in scenarios of variable amplitude loading. Alternative damage measures, such as the classical Miner and logarithmic Miner, are also considered for comparison between theoretical lifetime prediction and experimental data. The suitability of this approach is confirmed for it provides safe lifetime prediction when applied to fatigue data obtained for riveted joints made of a puddle iron original from the Fao bridge, as well as for data from experimental programs published elsewhere carried out for different materials (aluminium and concrete specimens) under distinct variable loading histories.

• 한국식품위생안전성학회지
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• 제21권3호
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• pp.189-195
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• 2006

이 연구는 통영지방에서 전통적으로 만들어지고 있는 충무김밥의 영양적 및 미생물학적 품질평가를 시도하였다. 일반김밥 중에서는 열량, Ca, Fe, 비타민$B_l$ 및 비타민$B_2$등이 한국 성인 남성의 권장량에 비하여 낮은 것으로 나타났다. 따라서 영양권장량을 맞추기 위해서는 부식과 과일 및 음료 등을 함께 섭취하여야 할 것으로 사료되었다. 시장에서 구입한 일밥김밥과 충무김밥의 총 호기성균 및 대장균군 수는 일반 김밥에서 $5.50{\pm}0.38 log_{10}CFU/g,\;2.10{\pm}0.47 log_{10}$ MPN/100g, 충무김밥에서 $5.61{\pm}0.42 log_{10}CFU/g,\;1.75{\pm}0.34log_{10}$ MPN/100 g로 각각 나타났다. 충무김밥의 원재료에 대한 총호기성 균수는 김밥, 주꾸미무침, 무김치에서 $3{\sim}4 log_{10}CFU/g$, 어묵에서 $4{\sim}5log_{10}$ CFU/g를, 대장균군은 김밥, 주꾸미무침, 무김치에서 $1{\sim}2log_{10}CFU/g$, 어묵에서 $2{\sim}3log_{10}CFU/g$으로 분석되었다. 충무김밥의 재료별 대장균과 포도상 구균의 검출율은 김밥에서 각각 10.0%,주꾸미무침에서 15.0, 10.0%, 무김치에서는 0, 10.0%가 각각 검출되었다. 일반김밥과 충무김밥을 $15^{\circ}C$에 저장하여 하룻밤 방치한 후에 측정한 균수는 일반김밥과 충무김밥에서 생균수가 1.04 및 $0.60 log_{10}CFU/g$, 대장균군이 0.97 및 $0.72 log_{10}MPN/100g$이 각각 증가하였다. 충무김밥 재료의 24시간 후에 총호기성 균수의 증가는 $0.83{\sim}1.33 log_{10}CFU/g$증가되는 것으로 조사되었다.

• 대한수학회논문집
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• 제14권3호
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• pp.569-579
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• 1999

We consider a random measure defined by the occupation time of Brownian motion in $l_2$. If it is normalized ${\lambda}^2$log then we show that its cluster set as ${\lambda}{longrightarrow}\infty$ can be represented by Ι-function on $\sigma$-finite measure in $l_2$.

• 한국전자거래학회지
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• 제7권2호
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• pp.157-171
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• 2002

We want to find a timestamping method which improves efficient performance and have high-level security to send secured messages in the digital signature and the law of e-commerces. Our paper shows a H-binary tree of time stamp to use a time stamp protocol with high security and performance in the packets of sending messages. We implement and analyze the protocols, show to compare with previous RSA methods. Our proposed protocol has O(log n) time complexity and high-performance.

• 지질공학
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• 제17권3호
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• pp.483-494
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• 2007

본 연구는 대단층이 발달하는 화산암 분포지역에서 암반 절취사면을 대상으로 단열의 발달특성과 이에 따른 암반분류 수정안을 제시하고자 수행되었다. 부산-울산 고속도로 건설 현장 중 해운대-기장 사이의 일광단층에 가까운 도로 절취사면 노두에서 단열계의 특성이 조사 분석되었다. 단열간격 분포의 경우 신장단열은 대수정규 분포를 보여주고 전단단열은 음의 지수 분포를 보여준다. 단열길이 누적빈도 분포 그림에서 중앙의 직선 구간이 1지점 -1.13, 2지점 -1.01, 3지점 -1.52의 지수를 가지며 멱법칙 스케일링을 지시한다. 각 지점에서 단열의 간격 및 밀도, 단열 간 교차점의 수 등을 분석하여 판단해 볼 때 암반의 안정성 및 강도는 1지점이 가장 낮고 2지점이 가장 높다. 한편, 각 지점에서 서로 연결된 단열의 최대 클러스터로 평가할 때 유체 이동의 능률은 3지점이 가장 높고 1지점이 가장 낮다. 이는 3지점이 상대적으로 단열의 길이가 긴 것들이 많으며 이들이 서로 연결하여 형성하는 최대 클러스터가 높은 비율로 전 지역에 고루 분포하고 있기 때문으로 볼 수 있다. 한편, 현장조사 자료를 토대로 응용통계기법을 이용하여 RMR 분류의 항목별 배점을 조정한 결과에 의하면, 대단층이 발달하는 화산암에서는 기존 RMR 분류 항목별 배점에 비해 현저히 다른 수정된 RMR 배점을 설정함이 타당한 것으로 나타났다. 분석결과 무결암 강도는 18, RQD는 61, 불연속면 간격 2, 불연속면 조건 2, 그리고 지하수 17의 배점이 나타났다.

• 대한수학회지
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• 제36권6호
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• pp.1133-1143
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• 1999

Chaterji strengthened version of a theorem for martin-gales which is a generalization of a theorem of Marcinkiewicz proving that if $X_n$ is a sequence of independent, identically distributed random variables with $E{\mid}X_n{\mid}^p\;<\;{\infty}$, 0 < P < 2 and $EX_1\;=\;1{\leq}\;p\;<\;2$ then $n^{-1/p}{\sum^n}_{i=1}X_i\;\rightarrow\;0$ a,s, and in $L^p$. In this paper, we probe a version of law of large numbers for double arrays. If ${X_{ij}}$ is a double sequence of random variables with $E{\mid}X_{11}\mid^log^+\mid X_{11}\mid^p\;<\infty$, 0 < P <2, then $lim_{m{\vee}n{\rightarrow}\infty}\frac{{\sum^m}_{i=1}{\sum^n}_{j=1}(X_{ij-a_{ij}}}{(mn)^\frac{1}{p}}\;=0$ a.s. and in $L^p$, where $a_{ij}$ = 0 if 0 < p < 1, and $a_{ij}\;=\;E[X_{ij}\midF_[ij}]$ if $1{\leq}p{\leq}2$, which is a generalization of Etemadi's marcinkiewicz-type SLLN for double arrays. this also generalize earlier results of Smythe, and Gut for double arrays of i.i.d. r.v's.

• Korean Chemical Engineering Research
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• 제62권1호
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• pp.53-69
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• 2024

The solubility of Cloxacillin sodium in ethanol, 1-propanol, isopropanol, and acetone solutions was measured at different temperatures. The melting property was also tested by using a differential scanning calorimeter (DSC). Then, the solubility data were fitted using Apelblat equation and λh equation, respectively. The Wilson model and NRTL model were not utilized to correlate the test data, since Cloxacillin sodium will decompose directly after melting. For comparison purposes, the four empirical models, i.e., Apelblat equation, λh equation, Wilson model and NRTL Model, were evaluated by using 1155 solubility curves of 103 solutes tested under different monosolvents and temperatures. The comparison results indicate that the Apelblat equation is superior to the others. Furthermore, a new method (named the calculation method) for determining the Apelblat equation using only three data points was proposed to solve the problem that there may not be enough solute in the determination of solubility. The log-logistic distribution function was used to further capture the trend of the correlation and to make better quantitative comparison between predicted data and the experimental ones for the Apelblat equation determined by different methods (fitting method or calculation method). It is found that the proposed calculation method not only greatly reduces the number of test data points, but also has satisfactory prediction accuracy.

• 대한수학회지
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• 제35권3호
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• pp.583-611
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• 1998

We consider a general class of real-valued Levy processes {X(t), $t\geq0$}, and obtain suitable large deviation results for the empiricals L(t, A) defined by $t^{-1}{\int^t}_01_A$(X(s)ds for t > 0 and a Borel subset A of R. These results are used to obtain the asymptotic behavior of P{Z(t) < a}, where Z(t) = $sup_{u\leqt}\midx(u)\mid$ as $t\longrightarrow\infty$, in terms of the rate function in the large deviation principle. A subclass of these processes is the Feller class: there exist nonrandom functions b(t) and a(t) > 0 such that {(X(t) - b(t))/a(t) : t > 0} is stochastically compact, i.e., each sequence has a weakly convergent subsequence with a nondegenerate limit. The stable processes are in this class, but it is much larger. We consider processes in this class for which b(t) may be taken to be zero. For any t > 0, we consider the renormalized process ${X(u\psi(t))/a(\psi(t)),u\geq0}$, where $\psi$(t) = $t(log log t)^{-1}$, and obtain large deviation probability estimates for $L_{t}(A)$ := $(log log t)^{-1}$${\int_{0}}^{loglogt}1_A$$(X(u\psi(t))/a(\psi(t)))dv$. It turns out that the upper and lower bounds are sharp and depend on the entire compact set of limit laws of {X(t)/a(t)}. The results extend to random walks in the Feller class as well. Earlier results of this nature were obtained by Donsker and Varadhan for symmetric stable processes and by Jain for random walks in the domain of attraction of a stable law.