• Ocean and Polar Research
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• v.41 no.3
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• pp.147-157
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• 2019

Our study was conducted to examine differences in incubation behavior among breeding sites and the relationship between factor affecting environmental change and incubation behavior of the Black-faced Spoonbill (Platalea minor). We set up the remote sensor cameras at three breeding sites (Mae-do, Namdongji, Guji-do) to observe incubation behavior in Gyeonggi Bay, South Korea from 2015 to 2018. We analyzed effects of breeding year, day of incubation started, day of incubation, the time of incubation exchanges and sex on incubation bout length. Mean incubation bout length of females (Mae-do: $7.19{\pm}0.23$ hours, Namdongji: $6.08{\pm}0.23$ hours, Guji-do: $7.96{\pm}0.30$ hours) was longer than males (Mae-do: $6.14{\pm}0.21$ hours, Namdongji: $5.45{\pm}0.28$ hours, Guji-do: $7.38{\pm}0.29$ hours). Mean incubation bout length was longer in Guji-do than other study sites. Incubation bout length tended to increase with the clutch initiation date. Males incubated their eggs at day time while female did at night time, these tendencies were observed more clearly in Guji-do. The proportion of time spent incubating of females was higher than males. Males' proportion increased as incubation progressed and increased rate in Guji-do was higher than other study sites. Our results showed that incubation rhythm of the Black-faced Spoonbill differed among breeding sites and varied with the environmental cycle.

• Asian-Australasian Journal of Animal Sciences
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• v.3 no.2
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• pp.121-123
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• 1990

A CRD experiment with unequal numbers of hens were assigned at random to three treatment groups, 1) separation of chicks from hen at 21 days after hatching 2) separation of chicks from hen at 7 days and 3) hens were allowed to brood the chicks(no separation) up to 10 weeks of age, to determine the productive and reproductive performance of hens and their chicks. The mean cycle length (one hatch to another) was 72.8 days for the 7-day group as compared with 87.7 days and 83.4 days for the 21-day and the no separation groups, respectively (p<.0l). The broody period was 28.5 days for the 7-day group compared with 43.9 and 42.6 days for the 21 days and the no separation groups, respectively (p<.0l). The end of the broody period to the start of lay varied from 8.0 to 8.7 days. The number of eggs laid per clutch were 12.3 for the 21-day group, compared with 11.5 and 10.1 for the 7-day and no separation groups, respectively (p<.05). This is due to the longer (p<.05) clutch length of the 21-day group as compared with the 7-day and no separation groups, respectively. The chicks separated from the hens at 21 and 7 days were heavier (p<.01) than the chicks not separated from the hens. Mortalities were highest (p<.05) for chicks separated at 7 days as compared with chicks separated at 21 days and those not separated. We concluded that separating chicks at 7 days from the hen gave the shortest cycle length and broody period, separating the chicks at 21 days gave the longest clutch length and the maximum number of eggs, separating the chicks at 21 and 7 days resulted in heavier chicks and separating the chicks at 7 days resulted in the highest mortality.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.519-519
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• 2023

Estuarine dams are a recent and global phenomenon. While estuarine dams can provide the benefit of improved freshwater resources, they can also alter estuarine processes. Due to the wide range of estuarine types and estuarine dam configurations, the effect of estuarine dams on estuaries is not well understood in general. To develop a systematic understanding of the effect of estuarine dam location and freshwater discharge interval on a range of estuarine types (strongly stratified, partially mixed, periodically stratified, and well-mixed), this study used a coupled hydrodynamic-sediment dynamic numerical model (COAWST) and compared flow, sediment transport, and morphological conditions in the pre- and post-dam estuaries. For each estuarine type, scenarios with dam locations at 20, 55 and 90 km from the mouth and discharge intervals of a discharge every 0.5, 3, and 7 days were investigated. The results were analyzed in terms of change in tide, river discharge, estuarine classification, and sediment flux mechanism. The estuarine dam location primarily affected the tide-dominated estuaries, and the resonance length was an important length scale affecting the tidal currents and Stokes return flow. When the location was less than the resonance length, the tidal currents and Stokes return flow were most reduced due to the loss of tidal prism, the dead-end channel, and the shift from mixed to standing tides. The discharge interval primarily affected the river-dominated estuaries, and the tidal cycle period was an important time scale. When the interval was greater than the tidal cycle period, notable seaward discharge pulses and freshwater fronts occurred. Dams located near the mouth with large discharge interval differed the most from their pre-dam condition based on the estuarine classification. Greater discharge intervals, associated with large discharge magnitudes, resulted in scour and seaward sediment flux in the river-dominated estuaries, and the dam located near the resonance length resulted in the greatest landward tidal pumping sediment flux and deposition in the tide-dominated estuaries.

• Journal of Korean Society of Transportation
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• v.23 no.8 s.86
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• pp.181-191
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• 2005

This study developed an algorithm for real-time signal control based on the detection system that can collect sectional travel time. The signal control variable is maximum queue length per cycle and this variable has a sectional meaning. When a individual vehicle pass through the detector, we can gather the vehicle ID and the detected time. Therefor we can compute the travel time of an individual vehicle between consecutive detectors. This travel time informations were bisected including the delay and not. We can compute queue withdrawing time using this bisection and the max queue length is computed using the deterministic delay model. The objective function of the real-time signal control aims equalization of queue length for all direction. The distribution of the cycle is made by queue length ratios.

• Korean Journal of Environmental Biology
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• v.21 no.4
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• pp.328-336
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• 2003

Biological and ecological characteristics of Diporeia spp. are described including size, growth, life cycle, energy storage, temperature effect, bioturbation, feeding depth and sediment ingestion of Diporeia. Bioaccumulation and toxicity of organic contaminants and trace metals were reviewed in addition to an examination of the relationships among various condition indexes (i.e. wet weight, dry weight and body length) of Diporeia.

• Development and Reproduction
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• v.23 no.4
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• pp.323-331
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• 2019

In this study, an experiment was conducted to investigate the annual reproductive cycle of a Korean flat bittering, Acheilognathus rhombeus, from Ogok-myeon located in Seomjin River. The reproductive cycle was examined histologically regarding water temperature and day length of the habitat, the gonadosomatic index (GSI), and developmental characteristics of female and male gonads. The maximum GSI was found to be 3.50±0.53 and 1.36±0.14 for females and males, respectively, when the water temperature and day light was 16.9℃ and 11.3 hours, respectively in October 2018. On the other hand, the minimum GSI was found to be 0.16±0.09 and 0.69±0.15 for males and females in December 2018 and February 2019, respectively. The ovipositor of females appeared from August to November 2018. We compared and calculated the stages of germ cell developmental characteristics in the testis and ovaries to determine the reproductive cycle. According to the result, we classified the female A. rhombeus reproductive cycle into four phases, which are ripe and spawning phase (October), degenerative phase (November to December), growing phase (January to March) and mature phase (April to September). The annual reproductive cycle of male A. rhombeus was categorized into four phases: mature phase (June to October), degenerative phase (November to March), resting phase (April) and growing phase (May). The Korean flat bittering is an autumn-spawner as the main spawning season in October. In male, testicular spermatogonia appeared all year-round, and the ripe and releasing phase, which is characteristics of the spawning season in other fish, did not appear.

• 한국ITS학회:학술대회논문집
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• v.2007 no.10
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• pp.64-69
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• 2007

• Animal cells and systems
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• v.3 no.4
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• pp.375-383
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• 1999

Gonadal development, gametogenesis, reproductive cycle, and first sexual maturity of Reishia clavigera were investigated monthly from July 1998 to June 1999 through cytological and histological observations. R. clavigera had separate sexes, and was an internal fertilizer. The ma1e penis was located near the two tentacles. The ovary and testis were composed of a great number of oogenic lobules and spermatogenic tubules, respectively. The size of ripe oocyte ranged from 130 to 140 ${\mu}$m in diameter. The peripheral cytoplasm of the germinal vesicle of the ripe oocyte in many cases were surrounded by smaller yolk granules, while the eccentric cytoplasm was occupied with larger ones. The reproductive cycle of R. clavigera could be classified into five successive stages: early active, late active, ripe, spawning, and recovery. Spawning of females occurred from early July to August when the seawater reached above 24.8$^{\circ}C$. Spawning of males occurred from early June to August in the water above 22.8$^{\circ}C$. Minimum size for sexual maturity of both sexes was above 10.0 mm in shell height. Each egg capsule was a cylinder or spindle in shape, 4-6 mm in length and 1-2 mm in width. Colors of newly spawned egg capsules showed yellowish white or pale yellow, while those with veliger larvae showed pale black, and released larvae or dead egg capsules showed black violet. The fecundity in an egg capsule ranged from 70 to 91 eggs (mean＝80.28 eggs).

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.257-264
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• 2002

This study presents a life-cycle cost (LCC) effectiveness of a concrete with lightweight aggregate. A number of researchers have made their efforts to develop a lightweight concrete, since it is difficult to apply conventional concrete using general aggregate to heavy self-weight structures such as long span bridges. In this study, an optimum design for minimizing the life-cycle cost of concrete slab bridges is performed to evaluate the life cycle cost effectiveness of the lightweight concrete relative to conventional one from the standpoint of the value engineering. The data of physical properties for new concrete can be obtained from basic experimental researches. The material properties of conventional one are acquired by various reports. This study presents a LCC effectiveness of newly developed concrete, which is made by artificial lightweight aggregate. A number of researchers have made their efforts to develop a lightweight concrete, since it is difficult to apply conventional concrete using general aggregate to heavy self-weight structures such as long span bridges. From the results of the numerical investigation, it may be positively stated that the new concrete lead to, the longer span length, the more economical slab bridges compared with structures using general concrete.

• The Research Journal of the Costume Culture
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• v.4 no.3
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• pp.383-394
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• 1996

Even it's not easy to in the cycle of the change without the qualification of the data, but we can try to figure out a cycle of change in fashion as Kroeber used content analysis. As content analysis with quantitative data increases the objectivity, especially in the case of highly complex materials like s appearance, multi-directional research method; quantitative and qualitative methods are combined in this study. In this research, first the change in hair length(HL), hair width(HW), hair height(HH) was examined to find out possible cyclic aspects of change in each elements and the significant relationships among the hair style was probed and the cyclic aspects between hair style elements and skirt style elements were compared. The data was analyzed by using Time series analysis and Pearson correlation coefficients. The statistical analysis of the hair style of 20th century showed that the hair style's elements changed independently and indicated the cyclic aspects in hair style as Kroeber's fashion cycle. To consider of this result, the hair style changed in a cyclic pattern, its pattern were different from skirt style's. And as hair style's change was affected by change, the hair styles change appeared during wars and disappeared during a social stabilization; this result supports social change theory.