• International conference on construction engineering and project management
• /
• 2011.02a
• /
• pp.575-581
• /
• 2011

A novel approach for analysis of criticality with respect to path and to activity in networks with fuzzy activity durations is proposed. After recalling the Yager ranking method, the relative degree of criticality of activities and paths are defined. An efficient algorithm based on path enumeration to compute the relative degree of criticality of activities and paths in networks with fuzzy durations is proposed. Examples of former researches are employed to validate the proposed approach. The proposed algorithm has been tested on real world project networks and experimental results have shown that the algorithm can calculate the relative degree of criticality of activities and paths in a reasonable time.

• Journal of Korea Water Resources Association
• /
• v.45 no.5
• /
• pp.431-444
• /
• 2012

This study investigated the differences between annual maximum series and annual maximum independent rainfall event series with relatively short and long rainfall durations. Annual maximum independent rainfall events were selected by applying various IETDs and thresholds to the hourly rainfall data in Seoul for the duration from 1961 to 2010. Annual maximum independent rainfall event series decided were then compared with the conventional annual maximum series. Summarizing the results is as follows. First, the effect of IETD and threshold was not beyond the expected level. For example, as the IETD increases, the frequencies of independent rainfall events decreased similarly in their rate for both with short and long durations. However, as the threshold increases, the frequency of those with rather long durations decreased much higher. Second, The mean rainfall intensity of the independent rainfall events was found to remain constant regardless of their duration. This indicates that the annual maximum rainfall intensity could be found in a rainfall event with longer durations. Lastly, the difference between the annual maximum rainfall series and the annual maximum independent rainfall event series with rather short rainfall durations was found significantly large, which decreases with longer durations. This result indicates that the conventional data analysis method, especially for small basins with short concentration time, could lead an unrealistic design rainfall with little possibility of occurrence.

• Journal of Communications and Networks
• /
• v.9 no.3
• /
• pp.213-218
• /
• 2007

Methods for symbol-by-symbol channel feedback and adaptation of symbol durations have been recently proposed. In this paper, we quantitatively analyze the gain in error-constrained data throughput due to such an extremely rapid adaptation of symbol durations to fast-time-varying channels. The results show that a symbol-by-symbol adaptation can achieve a throughput gain by orders of magnitude over a frame-by-frame adaptation.

• Journal of Ecology and Environment
• /
• v.31 no.2
• /
• pp.139-146
• /
• 2008

To clarify the relationship between the timing and the duration of flowering among populations, plants, and individual flowers, the dates of flower budding, flowering and deflowering were monitored for ten woody species from March 1 to June 30, in 2005, 2006 and 2007, in temperate deciduous forests at three sites of Namsan, and individual plants from seven woody species were monitored from March 1 to May 31, in 2006. Total durations of flower budding, flowering, and deflowering varied among the plant species. Three durations of these phenological stages of Stephanandra incisa were the longest (74 days, 109 days, and 101 days, respectively), and those of Prunus serrulata var. spontanea were the shortest (7 days, 7 days, and 4 days, respectively). For each species, phenological durations varied among years but were similar among the study sites in the same year. There was no relationship between flowering time and flowering duration on the population level. On the plant level, the duration of flower budding was over 11 days in all specie; S. incisa had the longest duration (73.3 days), and that of Styrax japonica was long as well (29.0 days), while that of Prunus leveilleana was the shortest (11.3 days). The longer the mean flower budding duration, the greater the difference among the plants within a species. The flowering duration of for S. incisa was 92.2 days, while that of Forsythia koreana was 27.2 days. The flowering durations of all other species were $10{\sim}20$ days. The deflowering duration was 92.0 days in S. incisa and <15 days in all other species. Differences among the plants in deflowering duration were smaller than those of the other phenological stages. In the species that flowered in April, the correlation coefficient between the flowering duration and the first flowering date was negative and significant. However, in the species that flowered in May, the correlation between flowering duration and the first flowering date was not significant. For individual plants of all species except for S. alnifolia, the earlier the flowering time, the longer the flowering duration. Differences between flowering time and flowering duration across years were significant in six species.

• Wind and Structures
• /
• v.19 no.3
• /
• pp.339-352
• /
• 2014

This paper discusses the appropriate duration for basic gust wind speeds in wind loading codes and standards, and in wind engineering generally. Although various proposed definitions are discussed, the 'moving average' gust duration has been widely accepted internationally. The commonly-specified gust duration of 3-seconds, however, is shown to have a significant effect on the high-frequency end of the spectrum of turbulence, and may not be ideally suited for wind engineering purposes. The effective gust durations measured by commonly-used anemometer types are discussed; these are typically considerably shorter than the 'standard' duration of 3 seconds. Using stationary random process theory, the paper gives expected peak factors, $g_u$, as a function of the non-dimensional parameter ($T/{\tau}$), where T is the sample, or reference, time, and ${\tau}$ is the gust duration, and a non-dimensional mean wind speed, $\bar{U}.T/L_u$, where $\bar{U}$ is a mean wind speed, and $L_u$ is the integral length scale of turbulence. The commonly-used Durst relationship, relating gusts of various durations, is shown to correspond to a particular value of turbulence intensity $I_u$, of 16.5%, and is therefore applicable to particular terrain and height situations, and hence should not be applied universally. The effective frontal areas associated with peak gusts of various durations are discussed; this indicates that a gust of 3 seconds has an equivalent frontal area equal to that of a tall building. Finally a generalized gust response factor format, accounting for fluctuating and resonant along-wind loading of structures, applicable to any code is presented.

• Korean Journal of Weed Science
• /
• v.32 no.3
• /
• pp.180-187
• /
• 2012

Panicum maximum, Panicum repens, Imperata cylindrica, Pennisetum polystachion and Cyperus rotundus are five rhizomatous grass weeds that exist and are problematic in the coconut lands of Sri Lanka. Rhizomatous weeds are the most difficult to control because of their vegetative reproduction by underground propagules. Therefore chemical and biological techniques have failed to control these weeds to acceptable levels. Experiments were conducted to investigate the impact of depth of burial, duration of sun drying or duration of air drying rhizomes of the selected weed species on germination. Depth of burial reduced germination of all species. Burying rhizomes at depths less than 10 cm inhibited germination of P. maximum and P. polystachion. Burying depths below 30~40 cm inhibited germination of all species. Sun drying or air drying rhizomes for durations less than 5 days inhibited germination of P. maximum and P. polystachion. Germinations of all species were inhibited by sun drying rhizomes for 15 days or air drying rhizomes for 20 days. Sun drying of rhizomes of all species for five days reduced the moisture content to a greater extent than air drying. The results indicated that burying rhizomes at the depthsbelow 30~40 cm, sun drying rhizomes for durations beyond 15 days or air drying rhizomes for durations beyond 20 days would be effective in controlling germination of these species. The investigations of the experiments also suggest that keeping rhizomes on the soil surface without burying, sun drying rhizomes or air drying rhizomes for durations of 5~15 days would produce weak plants.

• Speech Sciences
• /
• v.11 no.3
• /
• pp.7-21
• /
• 2004

The present study aims to investigate domain-initial strengthening phenomenon, which refers to strengthening of articulatory gestures at the initial positions of prosodic domains. More specifically, this paper presents the result of an experimental study of initial syllables with onset consonants (initial-syllable vowels henceforth) of various prosodic domains in English and Hamkyeong Korean, a pitch accent dialect spoken in the northern part of North Korea. The durations of initial-syllable vowels are compared to those of second vowels in real-word tokens for both languages, controlling both stress and segmental environment. Hamkyeong Korean, like English, tuned out to strengthen the domain-initial consonants. With regard to vowel durations, no significant prosodic effect was found in English. On the other hand, Hamkyeong Korean showed significant differences between the durations of initial and non-initial vowels in the higher prosodic domains. The theoretical implications of the findings are as follows: The potentially universal phenomenon of initial strengthening is shown to be subject to language specific variations in its implementation. More importantly, the distinct phonetics- phonology model (Pierrehumbert & Beckman, 1998; Keating, 1990; Cohn, 1993) is better equipped to account for the facts in the present study.

• Phonetics and Speech Sciences
• /
• v.8 no.3
• /
• pp.11-20
• /
• 2016

It is well known that vowels are shorter before voiceless consonants than voiced ones in English, as in many other languages. Research has shown that the ratio of vowel durations in voiced and voiceless contexts in English is in the range of 0.6~0.8. However, little work has been done as to whether the ratio of vowel durations varies depending on English variety. In the production experiment in this paper, seven speakers from three varieties of English, New Zealand, British, and American English, read 30 pairs of (C)VC monosyllabic words which differ in coda voicing (e.g. beat-bead). Vowel height, phonemic vowel length, and consonant manner were varied as well. As expected, vowel-shortening effects were found in all varieties: vowels were shorter before voiceless than before voiced codas. Overall vowel duration was the longest in American English and the shortest in New Zealand (NZ) English. In particular, vowel duration before voiceless codas is the shortest in New Zealand English, indicating the most radical degree of shortening in this variety. As a result, the ratio of vowel durations in varying voicing contexts is the lowest in NZ English, while American and British English do not show a significant difference each other. In addition, consonant closure duration was examined. Whereas NZ speakers show the shortest vowel duration before a voiceless coda, their voiceless consonants have the longest closure duration, which suggest an inverse relationship between vowel duration and closure duration.

• The Journal of the Acoustical Society of Korea
• /
• v.18 no.6
• /
• pp.84-88
• /
• 1999

The accurate estimation of segmental duration is crucial for natural-sounding text-to-speech synthesis. For predicting Korean segmental durations, conventional methods utilized phonemic context, part-of-speech context and locational information in prosodic phrase. In this paper, the tonal information of phonemes is employed for more accurate prediction. After defining two non-boundary tones and six boundary tones, we annotated the tonal label on each syllable of 400 sentences. To predict segmental duration using tonal information, we constructed neural networks with a real-valued output node predicting phonemic duration and trained them by backpropagation algorithm. Experimental results showed that the proposed features are effective for predicting Korean segmental durations, and we got 0.863 correlation coefficient of the observed durations and predicted ones.

• International conference on construction engineering and project management
• /
• 2009.05a
• /
• pp.393-399
• /
• 2009

This paper introduces an automated tool named Advanced Stochastic Schedule Simulation System (AS4). The system automatically integrates CPM schedule data exported from Primavera Project Planner (P3) and historical activity duration data obtained from a project data warehouse, computes the best fit probability distribution functions (PDFs) of historical activity durations, assigns the PDFs identified to respective activities, computes the optimum number of simulation runs, simulates the schedule network for the optimum number of simulation runs, and estimates the best fit PDF of project completion times (PCTs). AS4 improves the reliability of simulation-based scheduling by effectively dealing with the uncertainties of the activities' durations, increases the usability of the schedule data obtained from commercial CPM software, and effectively handles the variability of the PCTs by finding the best fit PDF of PCTs. It is designed as an easy-to-use computer tool programmed in MATLAB. AS4 encourages the use of simulation-based scheduling because it is simple to use, it simplifies the tedious and burdensome process involved in finding the PDFs of the many activities' durations and in assigning the PDFs to the many activities of a new network under modeling, and it does away with the normality assumptions used by most simulation-based scheduling systems in modeling PCTs.