• Journal of Advanced Marine Engineering and Technology
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• 제10권1호
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• pp.65-73
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• 1986

Surface fatigue crack propagation tests by plane bending fatigue were conducted on the welding specimens of an aluminium alloy, A5083-0, having an edge through thickness notch to study the fatigue crack growth characteristics. Moreover, the experiments were performed in order to clarify the fatigue crack initiation and growth. The properties of fatigue crack growth were quantitatively inspected in welded metal, heat-affected zone and base metal of the welding specimens. The main results obtained are summarized as follows: 1. It is found that the hardness distributions of A5083-0 aluminium alloy weldments are quite different with those of steel material weldments, so that the hardness distribution becomes lower in the following order: base metal, heat-affected zone and weld metal. 2. It is observed that the grain size of this specimen weldment appears to be almost equal to the base metal, when TIC welding method is adopted. 3. In a surface fatigue crack initiation and growth, the fatigue crack does not begin by opening-closing mechanism until hardening is saturated at the crack tip. 4. The fatigue crack growth characteristics of A5083-0 alluminium alloy weldments can be concluded.$${\frac{da}{dn}}=C({\Delta}K)^n=3.8{\times}10^{-9}{({\frac}{1}{2}{\Delta}S_t{\sqrt{{\pi}a}})}^{2.4}$$

• 한국결정성장학회지
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• 제20권3호
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• pp.117-124
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• 2010

For Ar=5, Pr=1.18, Le=0.15, Pe=2.89, Cv=1.06, $P_B$=20 Torr, the effects of impurity $(N_2)$ on thermally and solutally buoyancy-driven convection ($Gr_t=3.46{\times}10^4$ and $Gr_s=6.02{\times}10^5$, respectively) are theoretically investigated for further understanding and insight into an essence of thermo-solutal convection occurring in the vapor phase during the physical vapor transport. For $10K{\leq}{\Delta}T{\leq}50K$, the crystal growth rates are intimately related and linearly proportional to a temperature difference between the source and crystal region which is a driving force for thermally buoyancy-driven convection. Moreover, both the dimensionless Peclet number (Pe) and dimensional maximum velocity magnitudes are directly and linearly proportional to ${\Delta}T$. The growth rate is second order-exponentially decayed for $2{\leq}Ar{\leq}5$. This is related to a finding that the effects of side walls tend to stabilize the thermo-solutal convection in the growth reactor. Finally, the growth rate is found to be first order exponentially decayed for $10{\leq}P_B{\leq}200$ Torr.

• Kyungpook Mathematical Journal
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• 제45권1호
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• pp.105-114
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• 2005

In this paper we investigate the growth of finite order solutions of the differential equation $f^{(k)}\;+\;A_{k-1}(Z)f^{(k-l)}\;+\;{\cdots}\;+\;A_1(z)f^{\prime}\;+\;A_0(z)f\;=\;F(z)$, where $A_0(z),\;{\cdots}\;,\;A_{k-1}(Z)\;and\;F(z)\;{\neq}\;0$ are entire functions. We find conditions on the coefficients which will guarantees the existence of an asymptotic value for a transcendental entire solution of finite order and its derivatives. We also estimate the lower bounds of order of solutions if one of the coefficient is dominant in the sense that has larger order than any other coefficients.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.116-121
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• 2006

Numerical simulations for dendritic growth of crystals are conducted in this study by the level set method. The effect of order of difference is tested for reinitialization error in simple problems and authors founded in case of 1st order of difference that very fine grids have to be used to minimize the error and higher order of difference is desirable to minimize the reinitialization error The 2nd and 4th order Runge-Kutta scheme in time and 3rd and 5th order of WENO schemes with Godunov scheme are applied for space discretization. Numerical results are compared with the analytical theory, phase-field method and other researcher's level set method.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제23권5호
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• pp.447-456
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• 2020

Purpose: Food insecurity, which is the inability to obtain food or inadequate food consumption in terms of quality and quantity, has physical and psychological consequences on children's health. This study aimed to investigate the relationship between children's growth disorders and food insecurity in Qazvin city, Iran. Methods: A case-control study was conducted on 177 cases and 355 controls of children aged 3 to 6 years, who were referred to health centers in Qazvin city. The case group consisted of children with growth disorders. Data were obtained with the 18-item US Department of Agriculture questionnaire, a household socioeconomic questionnaire, a and growth monitoring card. The data were analyzed with using IBM SPSS Version 22.0, by independent sample t-test, chi-square test, and logistic regression. Results: A significant relationship was found between children's growth disorders and household food insecurity with (p<0.05, odds ratio [OR]=17.0, confidence interval [CI]=5.9, 48.8) and without hunger (p<0.05, OR=2.69, CI=1.4, 4.9). There were also significant relationships between children's growth disorders and socioeconomic status (p<0.05, OR=3.4, CI=1.4, 8.5), the duration of breastfeeding (p<0.05, OR=0.94, CI=0.9, 0.98), and children's ages (p<0.05, OR=0.94, CI=0.92, 0.96). Sex and birth order, and the age of the parents was not found to be significantly related with growth disorders. Conclusion: Lower socioeconomic status and household food insecurity were the important predictors of children's growth disorders. Policymakers should focus more on promoting steady employment and income among family members. Nutritional education for mothers is also recommended, in order to better meet the nutritional needs of the children.

• 한국자원식물학회지
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• 제14권1호
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• pp.38-42
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• 2001

양파의 직파재배를 안정화를 기하기 위한 일환으로 농도별로 조정한 생장조정제에 종자를 침지한 다음 포장에 파종하여 유묘의 초기생장성을 조사하였던 결과를 요약하면 다음과 같다. 1 식물생장조정제 처리 종자의 출아율은 BA, GA$_3$ 및 kinetin 이 각각 93.0, 94.3, 93.8%로 생장조정제별 차이가 거의 없었으나, 무처리 종자 80%보다는 훨씬 높았다. 2. 초장은 식물생장조정제 처리효과가 뚜렷하였는데, 그 정도는 GA$_3$, kinetin 및 BA순이었으며, GA$_3$,와 BA는 처리농도가 높을수록 초장이 컸던 반면, kinetin은 오히려 작아졌다. 3. 전개엽수는 식물생장조정제처리에 의해서 증가하였는데 식물생장제별 큰 차이는 없었다. 4. 유묘의 뿌리수는 식물생장조정제처리에 의해 뚜렷하게 증가하였는데. CA$_3$처리에서 가장 효과가 컸으며. 다음이 BA, kinetin 순이었다.

• Korean Journal of Mathematics
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• 제28권1호
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• pp.105-121
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• 2020

The principal objective of this paper is to introduce the ideas of relative 𝜑-type, relative 𝜑-weak type of entire functions of several complex variables and study some growth properties concerning them.

• 통상정보연구
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• 제10권1호
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• pp.329-347
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• 2008

The purpose of this study is to examine the causal relationship between the exchange rate and economic growth, and to induce policy implications. In order to test whether time series data is stationary and the model is fitness or not, we put in operation unit root test, cointegration test. And we apply Granger causality based on an error correction model. The results indicate that uni-dierctional causality between exchange rate and economic growth is detected. Exchange rate impacts on economic growth, but economic growth don't impact on exchange rate. The analysis of impulse reaction function shows that the impulse of exchange rate impacts on Korean economic growth in negative direction. We can infer policy suggestion as follows: The fluctuation of exchange rate much affects economic growth, thus we must make a stable policy of exchange rate to continue economic growth.

• 대한수학회보
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• 제33권3호
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• pp.487-496
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• 1996

Let f(z) be an entire function. Then the order $\rho(f)$ of f is defined by $$ \rho(f) = \overline{lim}_r\to\infty \frac{log r}{log^+ T(r,f)} = \overline{lim}_r\to\infty \frac{log r}{log^+ log^+ M(r,f)}, $$ where T(r,f) is the Nevanlinna characteristic of f (see [4]), $M(r,f) = max_{$\mid$z$\mid$=r} $\mid$f(z)$\mid$$ and $log^+ t = max(log t, 0)$.

• Bulletin of the Korean Chemical Society
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• 제20권9호
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• pp.1031-1034
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• 1999

Tin oxide films have been grown employing the chemical vapor deposition technique under reduced pressure conditions using tetramethyltin as the precursor and oxygen as the oxidant. An activation energy derived for the deposition reaction under representative deposition conditions has a value of 89±3 kJ mol-1, suggesting a typical kinetic control. Deposition rates of tin oxide films exhibit a near first order dependence on tetramethyltin partial pressure and a zeroth order dependence on oxygen partial pressure. This study provides the first quantitative information about the growth kinetics of tin oxide films from tetramethyltin by the cold-wall low-pressure chemical vapor deposition.