• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.04a
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• pp.341-344
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• 2007

본 논문에서는 계층적 공정 경쟁 개념을 병렬 유전자 알고리즘에 적용하여 계층적 공정 경쟁 기반 병렬유전자 알고리즘 (Hierarchical Fair Competition Genetic Algorithm: HFCGA)을 구현하였을 뿐만 아니라 실수코딩 유전자 알고리즘(Real-Coded Genetic Algorithm: RCGA)에서 좋은 성능을 갖는 산술교배(Arithmetic crossover), 수정된 단순교배(modified simple crossover) 그리고 UNDX(unimodal normal distribution crossover)등의 다양한 교배연산자들을 적용, 분석함으로써 개선된 병렬 유전자 알고리즘을 제안하였다. UNDX연산자는 다수의 부모(multiple parents)를 이용하여 부모들의 기하학적 중심(geometric center)에 근접하게 정규분포를 이루며 생성된다. 본 논문은 UNDX를 이용한 HFCGA모델을 구현하고 함수파라미터 최적화 문제에 많이 쓰이는 함수들에 적용시킴으로써 그 성능의 우수성을 증명 한다.

• Phonetics and Speech Sciences
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• v.3 no.2
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• pp.23-28
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• 2011

Electromagnetometers (EMA) have been widely used in articulatory studies as their temporal resolution can capture most speech activities and the fleshpoint information allows one to readily quantify and analyze tongue shape. However, the drawback is that the data lacks details of activity in the pharyngeal region. Several studies have attempted to estimate the unknown pharyngeal shape of the tongue, but few studies are based on unimodal data containing both front and back regions of the tongue at the same time. We use Stone's ball bearing method to obtain fleshpoint data as well as tongue shape. We further introduce a novel way of connecting balls and attaching them onto the tongue to ensure accurate tracking. An Artificial Neural Network is applied to build a map between observable flesh-points, unknown tongue shape, and pharyngeal region and is optimized to efficiently address nonlinearity.

• Journal of Powder Materials
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• v.5 no.2
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• pp.133-138
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• 1998

The effect of $\beta$-$Si_3N_4$ seeding on microstructural development of silicon nitride based materials has been investigated. In particular, to observe more distinctly the abnormal grain growth in pressureless sintering, fine $\alpha$-$Si_3N_4$(mean particle size: 0.26 ${\mu}m$) powder classified by sedimentation method was used. It was possible to prepare silicon nitride with abnormally grown grains under low nitrogen pressure of 1 atm thanks to the heterogeneous nucleation on $Si_3N_4$ seed particles. The size and morphology of silicon nitride grains were strongly influenced by the presence of $\beta$-$Si_3N_4$ seed and overall chemical composition. For specimens with initially low $\beta$-content, the large grains grew without a significant impingement by other large grains. On the contrary, for specimens with initially high $\beta$-content, steric hindrance was effective. The resulting microstructure was less inhomogeneous and characterized by unimodal grain size distribution.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.1 s.34
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• pp.77-85
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• 2005

Impedance spectroscopy was applied to low temperature polycrystalline Si in order to investigate the electrical/dielectric information in polycrystalline Si. By combined microstructure and impedance spectroscopy works, it was shown that the electrical information is sensitive to the corresponding microstructure, i.e., the grain size and distribution, judged from the capacitance vs. grain size relationship. At $360 mJ/cm^2$, the maximum in capacitance and the minimum in resistance correspond to the largest grain sizes of unimodal distribution in polycrystalline Si. The electrical/dielectric characterization is compared with Raman spectroscopic characterizations in terms of microstructure.

• Child Health Nursing Research
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• v.9 no.2
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• pp.131-139
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• 2003

Purpose: This study was meta-analysis study that it was to analyze the effect of sensory stimulation on preterm infants. Method: The sample of this study is 18 researches of selected by criteria. The conclusion of study was that sensory stimulation of preterm infants is effective. Result: Most large effect size was Katz(1991)'s study(d=1.96), small effect size was Caine(1991), s(d=0.37). Especially multimodal sensory stimulation(d=1.2) was more effective than unimodal sensory stimulation(0.53). Also behavioral variable of preterm infans was most sensitivity indicator. Conclusion: According to the result, the study on sensory stimulation should be research according to the gestational age and birth weight of preterm infants. In addition, the feasible sensory intervention should be develop.

• Geomechanics and Engineering
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• v.23 no.5
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• pp.431-439
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• 2020

Soil-water retention curve (SWRC) contains key information for the application of unsaturated soil mechanics principles to engineering practice. The SWRC variables are commonly used to describe the hydro-mechanics of soils. Generally, these parameters are determined using the graphical method which can be time consuming. The SWRC is highly dependent on the pore size distribution (PSD). Theoretically, the PSD obtained by mercury intrusion porosimetry test can be used to determine some SWRC variables. Moreover, the relationship between SWRC and shrinkage curve has been investigated. A new method to determine total SWRC variables directly without curve-fitting procedure is proposed. Substituting the variables into linear SWRC equations construct SWRC. A good agreement was obtained between predicted and measured SWRCs, indicating the validity of the proposed method for unimodal SWRC.

• Journal of the Korean Ceramic Society
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• v.23 no.5
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• pp.93-101
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• 1986

Microporous glasses were prepared from the 50 $SiO_2-44$ $B_2O_3-6$ $Na_2O$(wt%) parent glass by the phase eparation technique and were characterized by SEM, BET, and Gas Adsorption methods to investigate the possiblity of their use as salt-rejection membranes for reverse osmosis. The conditions of the phase separation for the possible glass membranes were optimized for the given parent glass. The temperature and duration of heat-treatment were desired to be lower(853K) and shorter (1/2~1 hr) respectively. The specific surface areas of porous glasses prepared in this study were about 80~120$m^2$/g and their pore size distribution had a unimodal shape(peak pore radius less than 15$\AA$) It was suggested that the porous glass obtained in this work could be effective for salt-rejection in point of pore size distributions but the way to increase its surface area for the high flux must be studied.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1069-1074
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• 2008

Tool condition monitoring (TCM) is crucial for improvement of productivity in manufacturing process. However, TCM techniques have not been applied to monitor tool failure in an industrial gear shaving application. Therefore, this work studied a statistical TCM method for monitoring gear shaving tool condition. The method modeled the shaving process using beta probability distribution in order to extract the effective features. Modeling includes rectifying for converting a bi-modal distribution into a unimodal distribution, estimating parameters of beta probability distribution based on method of moments. The usefulness of features obtained from the proposed method was evaluated and discussed.

• Ocean and Polar Research
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• v.24 no.2
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• pp.147-152
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• 2002

Seasonal and interannual variation of volume transport through the La-Perouse Strait were estimated using the difference of sea level observed at Krillion of Sakhalin, Russia, and Wakkanai of Hokkaido, Japan, during the period of 1975-1988. Historical sea level measurements between Russian and Japanese tide gauge data were normalized using an independent direct volume transport measurement. Volume transport from the East Sea (Sea of Japan) to the Sea of Okhotsk varied from -0.01 to 1.18 Sv with an annual mean value of 0.61 Sv. Monthly water transport rates showed a unimodal distribution with its maximum occurring in summer (August) and minimum in winter (December-February). The annual mean volume transport varied from 0.2 to 0.8 Sv during the period of 1975-1988 with the maximum variance of 0.6 Sv.

• Journal of the military operations research society of Korea
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• v.24 no.2
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• pp.162-169
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• 1998

This study presents an single machine scheduling algorithm minimize lateness of product by controlling machining speed. Generally, production scheduling uses the information of process planning. But the production scheduling algorithm has not considered the control of machining speed in its procedures. Therefore, the purpose of this study is to consider the machining speed in production scheduling algorithm for efficient production scheduling. Machining time and machining cost required to manufacture a piece of a product are expressed as a unimodal convex function with respect to machining speed, so it has minimal point at minimum time speed or the minimum cost speed. Therefore, because of considering the machining cost, the control of machining speed for the algorithm is executed between minimum speed and maximum speed. An example is demonstrated to explain the algorithm.