• Korean Journal of Soil Science and Fertilizer
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• v.1 no.1
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• pp.117-123
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• 1968

A simplest and best method to find out lime requirement for Korean soils is described. Twenty six top soil samples were collected from various localities and chemical characteristics were dertermined. Three different buffer curve methods were employed as the standard to find out the most reliable test for lime requirement. In addition, the lime requirement test by the Shoemaker's and Woodruff's as well as the O.R.D. kit method were compared with the most reliable buffer curve method. The results may be summarized as follows. 1. The regression equation of the most reliable lime requirement by buffer curve method, y, on percent base saturation of various soils, X, was y=9.69-0.106 X and the negative correlation coefficient r=-0.84 was statistically significant at 5% level. 2. Lime requirement test by the best, buffer curve, method was more well correlated with the sum of exchangeable hydrogen and exchangeable aluminum contents of the soil samples than the exchangeable hydrogen content only. 3. The ordinary buffer curve method for lime requirement is more reasonable than the lime requirement test by the buffer curve prepared after addition of 1 normal potassium chloride or calcium chloride solutions. 4. The lime requirement tests by the most reasonable buffer curve method, X, and by the Woodruff's, the Shoemaker's and O.R.D. kit were compared. The best method for laboratory lime requirement test was the Shoemaker's method and the O.R.D. kit method also was good enough for the field test and these two method are recommended as the unified method of lime requirement test in each soil testing laboratories throughout Korea.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.10a
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• pp.120-126
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• 1997

This paper examines the crack growth behavior of 7075-T651 aluminum alloy under high-low block loading condition. The cantilever beam type specimen with a chevron notch is used in this study. The crack growth and closure are investgated by compliance method. The applied initial stress ratios are R=-0.5, R=0.0 and R=0.25 Crack length($\alpha$), effective stress intensity factor range(ΔKeff), ratio of effective stress intensity factor range(U) and crack growth rate(d$\alpha$/dN) etc. are inspected fracture mechanics estimate.

• Research in Community and Public Health Nursing
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• v.19 no.2
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• pp.310-316
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• 2008

Purpose: The purpose of this study was to examine impulsivity and self-efficacy according to Internet addiction in adolescents. Method: Subjects were middle and high school students in Daegu (N=486). Data were collected by a self-rating questionnaire including demographic data, a Korean version of Internet addiction, impulsivity and self-efficacy. Result: Impulsivity and self-efficacy according to Internet addition were significantly different (F=22.909. p<.001). There were significant correlations between Internet addiction and impulsivity (r=.280. p<01), between Internet addiction and self-efficacy(r=-.288. p<.01) and between impulsivity and self-efficacy (r=-.665. p<.01). Conclusion: These results indicate that the more addictive to the Internet the more impulsive and the less self-efficacious. Therefore, further studies are needed to generalize these results and examine the effects of Internet addiction more broadly.

• Journal of applied mathematics & informatics
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• v.28 no.1_2
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• pp.217-231
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• 2010

We consider a class of elliptic problems of a logistic type $$-div(|{\nabla}_u|^{m-2}{\nabla}_u)\;=\;w(x)u^q\;-\;(a(x))^{\frac{m}{2}}\;f(u)$$ in a bounded domain of $\mathbf{R}^N$ with boundary $\partial\Omega$ of class $C^2$, $u|_{\partial\Omega}\;=\;+{\infty}$, $\omega\;\in\;L^{\infty}(\Omega)$, 0 < q < 1 and $a\;{\in}\;C^{\alpha}(\bar{\Omega})$, $\mathbf{R}^+$ is non-negative for some $\alpha\;\in$ (0,1), where $\mathbf{R}^+\;=\;[0,\;\infty)$. Under suitable growth assumptions on a, b and f, we show the exact blow-up rate and uniqueness of the large solutions. Our proof is based on the method of sub-supersolution.

• Membrane Journal
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• v.14 no.1
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• pp.53-56
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• 2004

Direct Methanol Fuel Cell (DMFC) is considered as a candidate technology for applications in stationary, transportation as well as electronic power generation purposes. To develop a high performance direct methanol fuel cell(DMFC), a competent electrolyte membrane is needed. The electrolyte membrane should be durable and methanol crossover must be low. One of the approaches to increase the stability of generally used polymer electrolyte membranes such as Nafion against swelling or thermal degradation is to bond it with an inorganic material physically or chemically. In Noritake Company, we have developed a novel method of reinforcing the polymer electrolyte matrix with inorganic fibers. Methanol crossover values measured were significantly lower than the original polymer electrolyte membranes. These fiber reinforced electrolyte membranes (FREM) were used for DMFC study and stable power output values as high 160 mW/$\textrm{cm}^2$ were measured. The details of the characteristics of the membranes as well as I-V data of fuel cell stacks are detailed in the paper.

• Proceedings of the Korea Contents Association Conference
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• 2016.05a
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• pp.341-342
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• 2016

제조 산업에서 키워드로 많이 다뤄지는 4M데이터(man, method, machine, martial)는 생산에 효율성을 높이기 위한 중요한 요소이다. 규모가 작은 기업일수록 4M관련 데이터 관리가 잘 안되고 있다. 관리를 잘하는 기업이라도 수집하고 저장만 하고 있는 현실이다. 본 논문에서는 수집하고 저장되어 있는 4M데이터를 활용해 생산한 상품에 대한 생산당시 상황을 추적할 수 있는 시스템을 제안한다. 제안한 시스템을 이용해 생산라인의 상황을 한 눈에 파악이 가능하고 주로 문제가 발생하는 공정과 관련 요인 파악을 통해 불량률을 줄이는 연구를 할 수 있다.

• Journal of the Korean Ceramic Society
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• v.31 no.4
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• pp.407-414
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• 1994

Compacts were prepared using the SHS(Self-propagating High-temperature Synthesis) method and nitrided at temperatures range from 145$0^{\circ}C$ to 175$0^{\circ}C$, and pressed at 180$0^{\circ}C$ under N2 atmosphere. The samples were characterized for bulk density, porosity, pore size and distribution, phase composition, microstructure and fracture toughness. Compacts were composed of whiskers, which showed a good candidate for the composite materials. The major phases of the compacts nitrided at 175$0^{\circ}C$ and pressed at 180$0^{\circ}C$ were 15R-sialon with a large aspect ratio.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2003.06a
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• pp.177-182
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• 2003

The robust output tracking control problem of general nonlinear MIMO systems is discussed. The robustness against parameter uncertainties is considered. In this paper, we proposed the robust output tracking control scheme for a class of MIMO nonlinear dynamical systems using output feedback linearization method. The presented control scheme is based on the VSS. We assume that the nonlinear dynamical system is minimum phase, the relative degree of the system is r$_{1}$＋r$_{2}$＋…r$_{m}$$\leq$ n and zero dynamics is stable. It is shown that the outputs of the closed-loop system asymptotically track given output trajectories despite the uncertainties while maintaining the boundedness of all signals inside the loop. And we verified that the proposed control scheme is then applied to the control of a two degree of freedom (DOF) robotic manipulator with payload.d.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.2
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• pp.133-141
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• 2011

In this study, different calibration approaches for reduced sulfur compounds (RSCs) were investigated by using thermal desorption coupled with gas chromatography (GC) and pulsed flame photometric detection (PFPD). To evaluate the effects of calibration procedures, gaseous standards of 4 RSCs ($H_2S$, $CH_3SH$, DMS, and DMDS) prepared at 10 ppm level were analyzed at 7 loading injection volumes (40, 60, 80, 100, 160, 240, and 320 ${\mu}L$). The results were then compared with calibration curves made with the Z (zero offset) and N (non-zero offset) method. The concentrations of unknown samples were then quantified by using R (ratio) method in which the slope values are compared between standards and samples. Secondly, in A (average) method, results obtained from a multi-point analysis of unknown samples were also averaged to extract representative values for each sample. Results of both experiments showed that analytical error of low molecular weight components (such as $H_2S$ and $CH_3SH$) was greatly expanded with the Z method. In conclusion, the combined application of N-A method was the more realistic approach to reduce biases in the quantification of RSCs.

• Korean Journal of Pharmacognosy
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• v.45 no.1
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• pp.84-87
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• 2014

A high performance liquid chromatography (HPLC) method for the quantitation of ellagic acid in Nymphaea tetragona was developed for the quality control of functional cosmetic ingredient, the extract of N. tetragona. Separation and quantitation were successfully achieved with a Kromasil C18 column ($5{\mu}m$, $250mm{\times}4.6mm$, i.d.) by isocratic elution of a mixture of acetonitrile containing 0.1% trifluoroacetic acid and water containing 0.03% phosphoric acid at a flow rate of 1.0 ml/min. The UV detector was used for the detection and the wavelength for quantitation was set at 254 nm. The presence of ellagic acid in the extract was determined by comparison of retention time and spiking with authentic standard. Analytical results showed good linearity ($R^2=0.99996$) in relatively wide concentration ranges. The R.S.D. for precision test was less than 3.0%. Recovery of the compound was 98.55~101.72% with R.S.D values less than 4.0%. In conclusion, this method has been successfully applied to the determination of ellagic acid in N. tetragona.