• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.4
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• pp.47-57
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• 1983

The parameter of impulse response of groundwater proposed by Kraijenhoff, that is, the reservoir coefficient j is determined on the basis of the least squares criteria. The degree (${\alpha}$) which expresses how much each sequential storm contributes to groundwater flow through the saturated soil is obtained by the optimization techniques which minimize deviations between observed and derived runoff hydrograph, and the convolution summation for the linear theory is used. A numerical example for this study is carried out for a storm event of Goose Creek basin near Leesburg, Virginia. As the results, the groundwater unit hydrograph and baseflow were able to be obtained. The used optimization technique is suited to the purpose of this study in case of the constraints. It is judged that the results allow the determination of baseflow.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.53-56
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• 2000

The problem ( Ρ ) of optimizing a linear function d$\^$T/x over the set of efficient set for a multiple objective linear program ( Μ ) is difficult because the efficient set is nonconvex. There some interesting properties between the objective linear vector ｄ and the matrix of multiple objectives C and those properties lead us to establish criteria to solve ( Ρ ) with a linear program. In this paper we investigate a system of the linear equations C$\^$T/${\alpha}$=d and construct two linearly independent positive vectors ${\mu}$, ν such that ${\alpha}$=${\mu}$-ν. From those vectors ${\mu}$, ν, solving an weighted sum linear program for finding an efficient extreme point for the ( Μ ) is a way to get an optimal solution ( Ρ ). Therefore our theory gives an easy way of solving nonconvex program ( Ρ ) with a weighted sum linear program.

• Journal of the Korean Magnetics Society
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• v.1 no.1
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• pp.1-5
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• 1991

The magnetic properties of the polycrystalline ${(Fe_{2}O_{3})}_{1-x-y}{(In_{2}O_{3})}_{x}{(Eu_{2}O_{3})}_{y}$(x=0.01, y=0.02과 x=0.02, y=0.03) have been studied by the methods of X-ray diffraction, $M\"{o}ssbauer$ effect, and magnetic hysteresis measurement. The X-ray diffraction patterns show that the samples have a same crystal structure as $\alpha-Fe_{2}O_{3}$. From the analysis of the temperature dependence of the quadrupole splitting and average half-width, it is found that the Morin transition occurs in the sample of x=0.01 and y=0.02 and the spin angle defined as the angle between the [111] crystal axis and antiferromagnetic vector, changes from about $35^{\circ}$ to the (111) plane as increasing the temperature in the sample of x=0.02 and y=O.03. The temperature dependence of magnetic hyperfine field is analyzed by using the spin-wave theory. The isomer shift values at room temperature are found to be given by about 0.35mm/s for the samples which means that the Fe ions belong to $3^{+}ion$. The temperature dependence of isomer shift was analyzed by using the Debye model.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.1
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• pp.116-122
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• 2016

Recently, the production cycle in manufacturing process has been getting shorter and different types of product have been produced in the same process line. In this case, the control chart using coefficient of variation would be applicable to the process. The theory that random variables are located in the three times distance of the deviation from mean value is applicable to the control chart that monitor the process in the manufacturing line, when the data of process are changed by the type of normal distribution. It is possible to apply to the control chart of coefficient of variation too. ${\bar{x}}$, s estimates that taken in the coefficient of variation have just used all of the data, but the upper control limit, center line and lower control limit have been settled by the effect of abnormal values, so this control chart could be in trouble of detection ability of the assignable value. The purpose of this study was to present the robust control chart than coefficient of variation control chart in the normal process. To perform this research, the location parameter, ${\bar{x_{\alpha}}}$, $s_{\alpha}$ were used. The robust control chart was named Tim-CV control chart. The result of simulation were summarized as follows; First, P values, the probability to get away from control limit, in Trim-CV control chart were larger than CV control chart in the normal process. Second, ARL values, average run length, in Trim-CV control chart were smaller than CV control chart in the normal process. Particularly, the difference of performance of two control charts was so sure when the change of the process was getting to bigger. Therefore, the Trim-CV control chart proposed in this paper would be more efficient tool than CV control chart in small quantity batch production.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5411-5416
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• 2013

To verify confidence of the measurement such as Firm performance of Entertainment system, Cronbach's alpha coefficient were measured and showed 0.7 or higher alpha values. Feasibility of the measurement is also ensured by exploratory factor analysis. This thesis are formulated and analyzed as two little hypotheses to make certain that systematization of entertainment company influences on the performance. As a result, the two hypotheses are significant influential factors on the performance of entertainment company. The result are somewhat predicted because it was constructed by theories and preceding research which the researcher had already recognized. But this study was conducted to provide suggestions to establish a theory of entertainment industry by active follow-up studies for resolving will-less different results in this field due to a lack of the proceding research. And it is required to be established through the academic interchange among the similar studies.

• Analytical Science and Technology
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• v.10 no.6
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• pp.403-407
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• 1997

Separation factor for $^6Li$ and $^7Li$ have been determined using ion exchange resin having 1,7,13-trioxa-4,10,16-triazacyclooctadecane($N_3O_3$) as an anchor group. The lighter isotope, $^6Li$ is concentrated in the solution phase, while the heavior isotope, $^7Li$ is enriched in the resin phase. By Ccolumnl chromatography[0.9cm(I.D)${\times}$20cm(height)] using 2.0M ammonium chloride solution as an eluent, single separation factor, ${\alpha}$, 1.009. i.e.$(^7Li/^6Li)_{resin}$/$(^7Li/^6Li)_{solution}$ was obtained by the Glueckauf theory from the elution curve and isotope ratios.

• Elastomers and Composites
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• v.22 no.3
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• pp.195-203
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• 1987

In this study, as one of the developing ways of the functional elastomer, improvement of the functionality of CB-BR was attempted through moisture curing reaction. The curing reaction of CB-BR was determined with an use of 3-aminopropyltriethoxysilane(APS) as a crosslinking agent, also a solution reaction with an active chlorine of CB-BR was elucidated by using a reaction kinetics theory and a study of physical property was made through moisture curing on the compound of 3-aminopropyltriethoxysilane and CB-BR The results of this study obtained are as follows : 1) CB-BR reacted easily with APS in the liquid state and the reaction rate coefficient and activation energy were as follows : 2) Optimum pressure condition of moisture cured elastomer(CB-BR+APS) was 20 minutes at $150^{\circ}C$, and the crosslinked elastomer was close to the theoretical value (q=1) for Flory's equation($\frac{\alpha}{\alpha-1}=q{\nu}RT$)

• Journal of KIISE:Databases
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• v.28 no.3
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• pp.315-323
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• 2001

The concept of vertical partitioning has been discussed so far in an objective of improving the performance of query execution and system throughput. It can be applied to the areas where the match between data and queries affects performance, which includes partitioning of individual files in centralized environments, data distribution in distributed databases, dividing data among different levels of memory hierarchies, and so on. In general, a vertical partitioning algorithm should support n-ary partitioning as well as a globally optimal solution for the generation of all meaningful fragments. Most previous methods, however, have some limitations to support both of them efficiently. Because the vertical partitioning problem basically includes the fuzziness property, the proper management is required for the fuzziness problem. In this paper we propose an efficient vertical $\alpha$-partitioning algorithm which is based on the fuzzy theory. The method can not only generate all meaningful fragments but also support n-ary partitioning without any complex mathematical computations.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.6
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• pp.1295-1305
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• 2017

There is SEED cryptosystem in domestic block cipher standard. This code was drafted by the Korea Information Security Agency (KISA) in October 1998 and underwent a public verification process in December of the same year, which resulted in the final amendment to improve safety and performance. Unlike DES, it is a 128-bit block cipher that has been passed through various processes and established in 2005 as an international standard. It is a block cipher with a pastel structure like DES, but the input bit block has been increased to 128 bits, double DES. In this paper, first, we introduce the general algorithm of SEED cryptosystem and analyzed mathematically generating principle of key-value which is used in F-function. Secondly, we developed a table that calculates the exponent of the primitive element ${\alpha}$ corresponding to the 8-bit input value of the S-function and finally analyzed calculating principle of S-function designed in G-function through the new theorem and example. Through this course, we hope that it is to be suggest the ideas and background theory needed in developing new cryptosystem to cover the weakness of SEED cryptosystem.

• The Korean Journal of Physiology and Pharmacology
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• v.28 no.4
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• pp.295-302
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• 2024

Walking can have a positive impact on cognitive function in adolescents. This study aimed to compare the effects of walking with sneakers and barefoot on cognitive ability in adolescents. Fifty-nine adolescent male students were included in the study and assigned to the control (n = 20), sneaker (n = 19), and barefoot (n = 20) groups. The barefoot and sneakers group performed a 40-min walking exercise four times a week for 12 weeks during the morning physical activity time, while the control group performed self-study. Electroencephalogram (EEG) and brain activity variables were measured before and after the exercise program. The results showed that after 12 weeks, the barefoot group had a significant decrease in Gamma and H-beta waves and a significant increase in sensorimotor rhythm (SMR) and Alpha waves. Conversely, the control group showed a significant decrease in SMR waves and increase in Theta waves. The sneaker group showed a significant decrease in SMR waves alone. In an eyes-open resting state, the barefoot group showed a significant increase in H-beta, M-beta, SMR, and Alpha waves. The barefoot group also had a significant increase in cognitive speed and concentration and a significant decrease in brain stress. Taken together, barefoot walking can effectively enhance cognitive ability in adolescents, as demonstrated by the significant variation in EEG activity. This research highlights the potential benefits of barefoot walking as a simple and effective form of exercise for enhancing cognitive function in adolescents.