• Proceedings of the Korea Association of Crystal Growth Conference
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• 1999.06a
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• pp.253-269
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• 1999

The development of telecommunication and information technology requires to develop new piezoelectric materials with small size, low impedance, wide pass band width and high thermal stability of frequency. Langasite (La3Ga5SiO14) single crystal has been researched substitute of quartz and LiNbO3 for the applications of SAW filter, BAW filter and resonator. Its single crystal growth has been carried out by Czochralski Method. So, in order to get single crystal with higher quality, in this study, lnagasite (La3Ga5SiO14) single crystal was grown by using Floating Zone (FZ) method and characterized. For the growth of langasite single crystals, the langasite powder was synthesized at 135$0^{\circ}C$ for 5hrs and the feed rod was sintered at 135$0^{\circ}C$ for 5hrs. The growing rate was 1.5mm/h and the rotation speed was 15 rpm for an upper rotation and 13 rpm for a lower rotation. In order to prevent the evaporation of gallium oxide, Ar and O2 gas mixture was flowed. The growth direction was analyzed by Laue back-scattered analysis. The composition of grown crystal was analyzed suing XRD and WDS. The electrical properties of grown crystal at various frequencies and temperature were discussed.

• Journal of Advanced Marine Engineering and Technology
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• v.10 no.1
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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.$${\frac{da}{dn}}=C({\Delta}K)^n=3.8{\times}10^{-9}{({\frac}{1}{2}{\Delta}S_t{\sqrt{{\pi}a}})}^{2.4}$$

• Kyungpook Mathematical Journal
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• v.45 no.1
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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.

• Proceedings of the SAREK Conference
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• 2006.06a
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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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• v.23 no.5
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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.

• Korean Journal of Plant Resources
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• v.14 no.1
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• pp.38-42
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• 2001

This study was conducted to stable direct sowing cultivation with seedling growth promotion by plant growth regulator treatment in onion seed(Allium cepa L.) The emergence percentage of soaked seed in BA, GA$_3$, and kinetin solution were higher than control seed, and those were 93.0, 94.3, 93.8%, respectively. The plant height was significant elongation in growth regulators treated seed, and those effects were high GA$_3$, kinetin and BA in the order, and the extend were high as increasing the growth regulator solution concentration in GA$_3$ and BA, and that was reverse in kinetin. The No. of leaf was increased in growth regulators treated seed, and the extend were similar among the growth regulators. The No. of root was increased significantly in growth regulators treated seed, and the extend were high in GA$_3$, BA and kinetin in the order.

• International Commerce and Information Review
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• v.10 no.1
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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.

• Journal of the Korean Data and Information Science Society
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• v.14 no.2
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• pp.313-323
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• 2003

For the growth curve model with arbitrary covariance structure, known as unstructured covariance matrix, the problems of detecting outliers are discussed in this paper. In order to detect outliers in the growth curve model, the test statistics using U-distribution is established. After detecting outliers in growth curve model, we test homo and/or hetero-geneous covariance matrices using PSR Quasi-Bayes Criterion. For illustration, one numerical example is discussed, which compares between before and after outlier deleting.

• Journal of the Korean Regional Science Association
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• v.15 no.1
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• pp.23-43
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• 1999

The strategy of regional industrial specialization is empirically evaluated by examining the relationship between regional industrial structures and economic performances. The regional industrial structure is measured by three industrial diversity indices such as ogive approach, entropy maximizing approach, and economic growth and employment instability in 12 regions is analyzed. According to the time series analysis, we found that the region with more diversified industrial structure experiences more stable in employment. Otherwise, the growth rate of the region with more simplified industrial structure is higher. Therefore, the strategy of industrial specialization is implemented in order to pursuit a rapid economic growth in the short run.

• Bulletin of the Korean Mathematical Society
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• v.33 no.3
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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 $log^+ t = max(log t, 0)$.