• Korean Journal of Hydrosciences
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• v.7
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• pp.107-124
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• 1996

Pipe design normally requires pump power, discharge or pipe diameter for each condition given. Due to several investigators the pipe friction factor con now be estimated by explicit way for a wide range of flow condition. In various problems of pipe design, however, the flow condition cannot be pre-determined even for a uniformly rough pipe. In these cases a lot of iterations are often required to have an accurate solution with ordinary approach. This paper presents the direct computation method of discharge and pipe diameter without any iteration process. Introducing the power law of friction factor, various non-dimensional physical numbers are derived such as power-diameter number, power-discharge number, diameter-slope number and discharge-slope number. One of the physical numbers concerned with discharge or pipe diameter can be related to a combination of the other in an explicit way.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.47-48
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• 2010

• Journal of the Korean Data and Information Science Society
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• v.17 no.3
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• pp.913-918
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• 2006

Chanas(2001) introduced the notion of interval approximation of a fuzzy number with the condition that the width of this interval is equal to the width of the expected interval. In this note, this condition is relaxed and the resulting formulae are derived for determining the approximation interval. This interval is compared with the expected interval and approximation interval of a fuzzy number as introduced by Chanas.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.1
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• pp.20-27
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• 1996

Greenhouse experiment was carried out to investigate the specifics in growth, weed competition, and herbicide response of soybean(Glycine max) under foggy condition. Plant height and leaf stage of soybean under foggy condition were greatly increased through all growing stage comparing with non-foggy condition. At 100 days after seeding, plant height of soybean also was increased by 14％ while number of pods, number of grains per pod were reduced by 16, 24 and 23％, respectively comparing with non-foggy condition. On the other hand, plant height of soybean under foggy condition was reduced with increasing the duration of competition and this tendency was similar to non-foggy condition. Plant height was reduced by above 50-day competition. Number of pods per plant of soybean was reduced regardless of foggy condition. Among the herbicides treated, quizalofop caused slightly crop injury under foggy condition, but the other herbicides did not affect growth of soybean. Number of pods and 100-grain weight of soybean by treatment of herbicides were similar to that of the untreated control but those of soybean under foggy condition were significantly reduced. At 40 days after herbicide application, weeding efficacy (based on shoot fresh weight) of herbicides treated under foggy and non-foggy condition, released exellent data(above than 97％) in all regardless foggy condition.

• International Journal of Highway Engineering
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• v.19 no.6
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• pp.97-103
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• 2017

PURPOSES : In this study, the pavement condition of non-mill-and-overlay and mill-and-overlay on deteriorated concrete pavement was compared. In addition, the suitable time to perform the initial overlay was investigated. METHODS : The condition of the pavement sections that were not additionally overlaid on non-mill-and-overlay or mill-and-overlay on deteriorated concrete pavements was investigated according to overlay pavement age. The condition of non-mill-and-overlay and mill-and-overlay sections of expressway route 25, which has more information on overlay history than other routes, was compared according to the number of times of overlay. The relation between the concrete pavement condition just before the overlay and the number of times of overlay was investigated for the non-mill-and-overlay and mill-and-overlay sections for which the first overlay was performed in the same year. RESULTS : The pavement condition of the non-mill-and-overlay sections was better than that of the mill-and-overlay sections, showing higher Highway Pavement Condition Index(HPCI) regardless of overlay pavement age. The number of reflection crackings of the non-mill-and-overlay sections was smaller than that of the mill-and-overlay sections. As a result of observing the cores obtained from the overlay sections, the proportion of the deteriorated non-mill-and-overlay sections was smaller than that of the mill-and-overlay sections. The SD measured just before the overlay on the concrete pavement for which additional overlay was not performed was smaller than that for which additional overlay was performed regardless of the milling of the concrete slab surface. The HPCI of the concrete pavement for which overlay was performed just once was higher than that for which overlay was performed more than one time. CONCLUSIONS : Accordingly, it was concluded that the condition of the non-mill-and-overlay sections was better than that of the mill-and-overlay sections. In addition, the better the condition of concrete pavement just before the initial overlay, the longer the duration of the overlay effect.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.2
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• pp.268-273
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• 1994

The quality of Kimchi was investigated under airtight and ventilating conditions. At 2$0^{\circ}C$ and 4$^{\circ}C$ fermentation, there were no significantly difference in pH, acidity and vitamin C of Kimchi between airtight and ventilating conditions. The contents of $CO_2$ , the number of lactic acid bacteria and the sensory score of carbonated taste under airtight condition were higher than those values under ventilating condition. While , the number of aerobic bacteria under airtight condition was lower than those under ventilating condition.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.578-582
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• 2005

In this study, the conceptual foundation and development process of the Antecedent soil Moisture Condition(AMC) in SCS runoff curve number method are reviewed. Although the runoff volume is very sensitive with AMC condition, the AMC class limits developed in SCS(1972) are used in rainfall-runoff analysis without careful consideration. Tn this study, following the SCS curve number development process, rainfall-runoff characteristics of the Jang-Pyung subbasin subject to the Pyung-Chang River basin are analyzed to evaluate the reasonability of the AMC class limits at present. The New AMC class limits are proposed by the sensitive analysis of the antecedent rainfall - curve number value. As a result, the classification value of AMC-I with II is 22mm of antecedent 5-day rainfall amount, and the classification of AMC-II with III is 117mm in growing season. When the New AMC class limits are applied to Jang-Pyung subbasin, AMC probability distribution shows that the AMC-II has increased remarkably even though the AMC-I has a little higher value. But the AMC-III has the smallest one. According to the conceptual basis of the curve number method, the AMC probability distribution, the New AMC class limits adopted, gives reasonable results.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.10
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• pp.2751-2761
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• 1994

A numerical investigation on the three-dimensional laminar natural convection heat transfer in the periodically fully developed PCB channel has been performed. When heat generating blocks mounted on the adiabatic wall make a channel with their facing shrouding wall, the flow inside the channel becomes periodically fully developed. A single module in the periodically fully developed region is chosen for computational domain in order to save computer storage and computational time. The periodic boundary condition is applied in the anlaysis. The effects of the parameters such as the Rayleigh number, the number of the modules, and the height of channel are examined to obtain the optimum condition for the enhancement of the cooling effectiveness. The result shows that the cooling effect is improved with increasing Rayleigh number and channel height, and decreasing the number of the module. The result also indicates that increasing the height of the channel and number of the module is recommended for a limited space.

• Korean Journal of Cognitive Science
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• v.19 no.1
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• pp.57-74
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• 2008

This study aimed to investigate the preferential brain activations involed in the set size during random number generation (RNG). The BNG condition gave more increased activations in the anterior cingulate cortex (ACC), inferior frontal gyrus (IFG), inferior parietal lobule (IPL), and superior temporal gyrus (STG) than the simple counting condition, which was a control rendition. When the activations were compared by the small set size condition versus the large set size condition, broad areas covering tempore-occipital network, ACC, and postcentral gyrus were more highly activated in the small set size condition than in the large set size condition, while responses of areas including medial frontal gyrus, superior parietal lobule, and lingual gyrus were more increased in the large set size condition than in the small set size condition. The capacity hypothesis of working memory fails to explain the results. On the contrary, strategy selection hypothesis seems to explain the current observations properly.

• Korean Journal of Cognitive Science
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• v.20 no.4
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• pp.573-601
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• 2009

The present study investigated the perceptual span during reading Korean, using the moving-window display change technique introduced by McConkie and Rayner(1975). Eight different window sizes were used in Experiment 1. They were 3, 5, 7, 9, 11, 13, 15 characters in size and the full line. Reading rate, number of fixation, saccadic distance, fixation duration were compared between each window-size condition and the full line condition. The reading rate was no higher in the full line condition than in the 15 character condition but was higher than in the other conditions. The number of fixations was no larger in the full line condition than in the 15 character condition, had a tendency to be larger than in the 13 characters condition, and was more than in the other conditions. The result pattern of the saccadic distance based on character was the same as that of the reading rate, and the saccadic distance based on the pixel was the same as that of the number of fixation. Similarly, for fixation duration, there was no differences between whole line condition and 15, 13, and 11 characters condition. The fixation duration had a tendency to be shorter in the 9 characters, and was shorter in the 7, 5, and 3 characters conditions than whole line condition. In Experiment 2, based on asymmetry of perceptual span, the 6 different window sizes(0, 1, 2, 3, 4 characters in size and the full line) were used. There was a difference only between the 0 condition and the other conditions in the reading rate, number of fixations, fixation duration. Considering the pattern of eye-movement measures above, the perceptual span of Korean readers extends about 6-7 characters to the right of fixation and 1 character to the left of fixation.