• Journal of Korea Water Resources Association
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• v.39 no.9 s.170
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• pp.767-777
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• 2006

The goal of this study is to improve Huff's method which is the most popular method for rainfall time distribution in Korea. As the first step, we reevaluated the context of Huff's original research motivations, geography and rainfall pattern of study area, and compared that to Korean situations. In original Huff's results, no change in temporal distribution characteristics were found for different rainfall durations. This was found to be different from Korean situations. Furthermore, results from the MOCT(Ministry of Construction and Transportation) version of Huff's method is on a gage basis not on a watershed basis, thus making it difficult to select cumulative rainfall curves representative of a watershed. In addition, all rainfall data regardless of their magnitude were used in the MOCT version of Huff' method which is different from original Huff's which screened out data by using a threshold value of 25.4mm. For both point and areal mean rainfall, time distribution characteristics of rainfall for various durations were found to be different. This was statistically proven by K-S test at 5% significance level as some cumulative rainfall curves developed from the rainfall data of certain durations were found to be not significant with cumulative rainfall curves developed from the rainfall data of all durations. Therefore, in order to apply Huff's method to Korean situations, it is recommended that dimensionless cumulative curve must be developed for various rainfall duration intervals using rainfall data greater than a certain threshold value.

• Korean Journal of Construction Engineering and Management
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• v.6 no.4 s.26
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• pp.80-90
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• 2005

Activity durations retain probabilistic and stochastic natures due to diverse factors causing the delay or acceleration of activity completion. These natures make the final project duration to be a random variable. These factors are the major source of financial risk. Extending the Stochastic Project Scheduling Simulation system (SPSS) developed in previous research; this research presents a method to estimate how the final project duration behaves when activity durations change randomly. The final project cost is estimated by considering the fluctuation of indirect cost, which occurs due to the delay or acceleration of activity completion, along with direct cost assigned to an activity. The final project cost is estimated by considering how indirect cost behaves when activity duration change. The method quantifies the amount of contingency to cover the expected delay of project delivery. It is based on the quantitative analysis to obtain the descriptive statistics from the simulation outputs (final project durations). Existing deterministic scheduling method apply an arbitrary figures to the amount of delay contingency with uncertainty. However, the stochastic method developed in this research allows computing the amount of delay contingency with certainty and certain degree of confidence. An example project is used to illustrate the quantitative analysis method using simulation. When the statistical location and shape of probability distribution functions defining activity durations change, how the final project duration and cost behave are ascertained using automated sensitivity analysis method

• Water for future
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• v.19 no.3
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• pp.249-258
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• 1986

The purpose of this study is to estimate the PMP frequency factor for evaluation of the Probable Maximum Precipitation (PMP) in Korea. The value of PMP is the criterion of the determination of design rainfall in Planning and designing hydraulic structures, and water resources management. To obtain the object, 12 key stations were selected in which have the automatic rain0recording paper of 20 years, and the annual maximum rainfall values were calculated for each 7 durations(10 min., 1, 2, 4, 6, 12, 24 hr.). The statistics(mean, standard deviation)were estimated, and diagram which shows the relationship between mean annual maximum rainfall($$) and frequency factor for each durations were drawn. PMP was estimated by statistical method using the PMP frequency factor obtained from the diagram and statistics($$, Sn). The PMP-Duration Equation was derived from the envelope curve in order to obtain the PMP for an arbitrary duration. The isohyetal map of 24 hours PMP and PMP. DAD curve for the whole of Korea were drawn in accordance with the point PMP values.

• Proceedings of the Korean Reliability Society Conference
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• 2002.06a
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• pp.263-272
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• 2002

Reliability of multi-phased mission system is represented where redundant components are repairable. Failures and repairs of components follow Markovian property Under some constraints, 4 models are available. Two models are represented here. The solutions are obtained as recursive equations using Markov model and eigenvalue system.

• Proceedings of the Korean Society of Crop Science Conference
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• 2018.04a
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• pp.196-196
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• 2018

• Proceedings of the Korean Nuclear Society Conference
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• 1999.05a
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• pp.355-356
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• 1999

• Proceedings of the Korean Society of Crop Science Conference
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• 2018.10a
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• pp.253-253
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• 2018

• Proceedings of the Korean Society of Crop Science Conference
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• 2018.10a
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• pp.255-255
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• 2018

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.E2
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• pp.97-106
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• 2002

The purpose of this study was to quantitatively estimate the washout removal efficiencies of criteria air pollutants such as SO$_2$, TSP, PM10, CO, NO$_2$, and O$_3$corresponding to the amounts and durations of precipitation. The removal patters by washout were studied with air pollutants data and the corresponding precipitation data in Seoul, Korea during the periods of 1990 to 1999. In addition, washout patterns were classified into four seasons and four time Bones, i.e., night, morning, afternoon, and evening. In this study, natures of air pollutants by sequential precipitation were also intensively studied by examining the linear relationships between removal efficiencies and the amounts and durations of precipitation for each pollutant. The results of this study showed that SO$_2$, TSP, and O$_3$were rapidly removed by initial precipitation; however, NO$_2$was slowly removed 2-hour after precipitation. Both CO and PM10 were weakly removed by washout and their removal patters showed to be irregular.

• Preventive Nutrition and Food Science
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• v.22 no.3
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• pp.211-215
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• 2017

The individual Maillard reactions of glucose, glucosamine, cyclohexylamine, and benzylamine were studied at a fixed temperature of $120^{\circ}C$ under different durations by monitoring the absorbance of the final products at 425 nm. Glucosamine was the most individually reactive compound, whereas the reactions of glucose, cyclohexylamine, and benzylamine were not significantly different from each other. Maillard reactions of reaction mixtures consisting of glucosaminecyclohexylamine, glucosamine-benzylamine, glucose-cyclohexylamine, and glucose-benzylamine were also studied using different concentration ratios under different durations at a fixed temperature of $120^{\circ}C$ and pH 9. Maillard reactions in the pairs involving glucosamine were observed to be more intense than those of the pairs involving glucose. Finally, with respect to the concentration ratios, it was observed that in most instances, optimal activity was realized, when the reaction mixtures were in the ratio of 1:1.