• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.371-376
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• 1998

In this study, the size effect of concrete members subjected to the axial load and bending moment is investigated using a series of C-shaped specimens of which test procedure is similar to those of Hognestad, Hanson, and McHenry's. Main test variable is a size ratio of the specimens(1:1/2:1/4) at the concrete compressive strength of 500kg/㎠. Test results show that the flexural compression strength at failure decreases as the size of specimen increases, that is, the size effect law is present. Model equation is derived using regression analyses with experimental data and it is compared with formulas for compressive strength of cylinders and shear strength of beams without stirrups. Size effects is distinct th following sequence; shear strength of beams without stirrups, compressive strength of C-shaped specimens, compressive strength of cylinders.

• The Korean Journal of Ecology
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• 제17권4호
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• pp.453-461
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• 1994

Size class structure and vegetative growth of a perennial herb of the temperate deciduous forests, Symplocarpus renifolius Schott, were studied from 1991 to 1994 in Namhansansung, Kyonggi Province, Korea. The size class structures of leaf number and leaf area per individual followed bell-shape curve, i.e. frequency of middle class was relatively high. The leaf area increased from the late-March to mid-May. At the end of the growing season, leaf area(length X breadth) was proportional to biomass, especially aboveground biomass. The leaf number and leaf area per individual increased at the rate of 0.08 leaf/year and 9.7 $cm^2/year$, respectively. The size of the individuals in large-sized classes, in leaf number and leaf area, decreased in next year, while the size of the individuals in small-sized classes increased. Therefore, it was concluded that the size class structure of S. renifolius population was largely determined by the growth form.

• Journal of the Optical Society of Korea
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• 제18권2호
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• pp.184-187
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• 2014

This study examined the effects of particle size on the light scattering of a nano-sized color filter pigment used to obtain a range of colors in liquid crystal displays. The contrast ratio is one of the most important characteristics of liquid crystal displays. When a color filter is located between two crossed polarizers, the size of the pigment can give rise to a decrease in the contrast ratio due to Rayleigh scattering by the nanoparticles in the filter. The size effect of the color filter pigment on the contrast ratio was investigated in terms of the depolarization parameter. As an experimental result, the depolarization parameter increased with decreasing pigment size. Therefore, a smaller pigment size can reduce light leakage caused by light scattering in the color filter between two crossed polarizers. The depolarization function was also proposed as a useful function for predicting the decrease in the contrast ratio of the color filter.

• 산업경영시스템학회지
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• 제29권1호
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• pp.34-40
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• 2006

Many producers put sampling inspection policy into the way of their convenience. Examples of the convenience are irregular lot size and too small sample size. Because they don't use a standard sampling inspection policy, they can not guarantee the quality level of their products. In this study, we developed a user-centered design program which can calculate the AOQL of their products to their buyers in the case of irregular lot size and too small sample size. Also this program propose a linear inspection cost by Hald's model.

• Bulletin of the Korean Chemical Society
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• 제25권3호
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• pp.351-356
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• 2004

Selected MPEG-b-PDLLA block copolymers have been synthesized by ring-opening polymerization with systematic variation of the chain lengths of the resident hydrophilic and hydrophobic blocks. The size and shape of the micelles that spontaneously form in solution are then controlled by the characteristics of the block copolymer template. All the materials prepared in this study showed the tunable pore size of 20-80 ${\AA}$ with the increase of hydrophobic chain lengths and up to 660 $m^2$/g of specific surface area. The formation mechanism of these nanoporous structures obtained by controlling the micelle size has been confirmed using both liquid and solid state $^{13}C\;and\;^{29}Si$ NMR techniques. This work verifies the formation mechanism of nanoporous structures in which the pore size and wall thickness are closely dependent on the size of hydrophobic cores and hydrophilic shells of the block copolymer templates.

• 대한안전경영과학회지
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• 제13권4호
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• pp.171-177
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• 2011

This paper reviewed the relationship between internal marketing and incremental innovation, and the moderating effect of firm size. The results of hierarchical multiple regression analysis, based on the responses from 322 employees in small business, showed that almost internal marketing factors effects positively on incremental innovation. All internal marketing factors(CEO support, compensation system, education & training, internal communication, authority delegation) appeared to be related positively with process innovation and service innovation. And all other factors(compensation system, education & training, internal communication, authority delegation) except CEO support showed to have positive relationship with operation innovation. In the moderating effects, internal communication effects more positively on incremental innovation in large firm-size than in small firm-size. But delegation effects more positively on incremental innovation in small firm-size than in large firm-size.

• 산업경영시스템학회지
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• 제21권45호
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• pp.357-364
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• 1998

This study deals with the performance evaluation of writing for designing handwriting instruments ergonomically. Experimental tests were executed on ballpoint pen., felt-tip pen, pencil, sharp-pencil, and fountain pen for ease of use and reduction of the muscles fatigue. The writing time and the degree of comfort of writing by subjects were measured on the diameters of five writing instruments. The results indicated that the ballpoint pen was rated significantly superior to the others in writing speed attribute and the instrument with the least fatigue was the fountain pen. There was a significant interaction effect between the types of instruments and their size in diameters. The diameter of instruments for considering time and comfort together was verified that the size of 9.5mm was efficient for ballpoint pen, the size of 8.1mm for felt-tip pen, the size of 7.5mm for pencil, the size of 8.2mm for sharp-pencil, and the size of 9.1mm for fountain pen.

• 산업경영시스템학회지
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• 제22권49호
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• pp.11-21
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• 1999

The purpose of this study is to present the method to select optimal size for the industrial products which are closely related to human's body size. For this purpose, human factors such as body characteristics, body features, and preference in product selection which needs to be considered in setting standards were analyzed. This analysis is to select optimal size to minimize losses caused by the difference of size between demand by the customers and supply from the manufacturers. Using loss function, repetitive calculation process algorithm by using bisearch method was applied in selecting the sizes of demand and supply which minimize the total expected losses. For cumulative normal distribution probability, IMSL routine DNORDF was used. In case study, comparison has been made between the result which was calculated using presented algorithm and the results calculated by the process currently used by KS and ISO by measuring aged women's body size in human factors side and sorting them through the factor analysis and cluster analysis for feature factor extraction. Thus, they can be used as a basis for establishing industrial product standards.

• 반도체디스플레이기술학회지
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• 제18권4호
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• pp.46-50
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• 2019

In this paper, We used the regression model of machine learning for improve the print quantity problem when which print scaffold with 400 ㎛ pore using FDM 3d printer. We have difficult to experiment with changing all factors in the field. So we reduced print quantity by selected two factors that most impact the pore size. We printed and measured scaffold 5 times under same conditions. We created regression model using scaffold pore size and print conditions. We predicted pore size of untested print condition using the regression model. After print scaffold with 400 ㎛ pore, we printed scaffold 5 times under same conditions. We compare the predicted scaffold pore size and the measured scaffold pore size. We confirmed that error is less than 1 % and we verified the results quantitatively.

• Journal of Magnetics
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• 제20권1호
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• pp.21-25
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• 2015

Fine Nd-Fe-B-type particles were prepared by ball milling of different types of Nd-Fe-B precursor materials, such as die-upset magnet, HDDR-treated material, and sintered magnets. Coercivity dependence on the grain and particle size of the powder was investigated. Coercivity of the milled particles was reduced as the particle size decreased, and the extent of coercivity loss was dependent upon the precursor material. Coercivity loss in the finely milled particles was attributed to the surface oxidation. The extent of coercivity loss in the fine particles was closely linked to grain size of the precursor materials. Coercivity loss was more profound for the fine particles with larger grain size. Contrary to the fine particles from the sintered magnets with larger grain size the fine particles (~10 um) from the die-upset magnet and HDDR-treated material with much finer grain size still retained high coercivity (> 10 kOe for die-upset magnet, > 4 kOe for HDDR-treated material).