• Korean Journal of Environmental Biology
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• v.23 no.4
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• pp.367-373
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• 2005

We conducted a year-long survey in 2000 to examine seasonal fluctuations in the abundance of the demersal copepod Pseudodiaptomus sp., the dominant copepod in the Seomjin River estuary, where the spring tide strongly affects changes in salinity gradients. Pseudodiaptomus sp. was found throughout the year in the entire range of salinities measured, but most individuals appeared at oligohaline conditions below 5.0 psu, and less than $2\%$ were observed in polyhaline conditions above 18.0 psu. The peak abundance occurred during autumn in oligohaline waters, and the density was relatively low during the rainy season in summer. In spring and autumn, copepodites were most abundant in oligohaline waters, although they were also fairly abundant in mesohaline conditions $(5\~18\;psu)$. Females with egg sacs appeared in oligo- and mesohaline waters during spring and autumn but were seldom found in polyhaline conditions throughout the year. Our results indicate that, despite the strong physical influence of the tide, Pseudodiaptomus sp. can manipulate its position to remain at its preferred salinity. We also found that spawning mainly occurred in oligohaline waters twice a year.

• Fisheries and Aquatic Sciences
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• v.6 no.4
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• pp.220-224
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• 2003

In order to determined the appropriate processing season of Pacific oyster (Crassostrea gigas), 30 individuals cultured in Kamak Bay on the southern coast of Korea were taken bimonthly 7 times a year, and seasonal variation of edible portion weight, edible portion yield and coefficient of fatness were investigated. There were close relationships between edible portion weight (X) and total weight (Y) and between coefficient of fatness (X) and edible portion yield (Y), which were expressed in regression lines, i.e. Y=0.2709X-1.9094 (r=0.9254) and Y=44.0596X+ 15.1127 (r=0.8485), respectively. From the results of seasonal variation of edible portion weight, yield and coefficient of fatness, the appropriate processing season of raw Pacific oyster was between winter and spring, that is, between December and following April the next year.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.1
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• pp.18-24
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• 1989

The effect of soil physico-chemical properties of pre and post soil preparation and permanent bed period on growth and yield was analysed by two models of annual variation and percent annual change (PAC). 1. Aggregation, porosity, bulk density except moisture were significantly different in each year from preparation to the 6th year while all soil chemical properties except Mg were significantly different in each year. 2. Soil physical properties showed significant simple correlation with yield and negative with the missing plant rate in each year while the electroconductivity ($EC_5$) of the 4th year showed significant correlation with yield. 3. Yield showed significant positive correlation with the variation of aggregation in permanent bed period, and negative with variation and PAC of aggregation of preplanting soil and variation of moisture in permanent bed period. Missing plant rate was negatively correlated with porosity variation of preplanting soil and positively with PAC of aggregation in preplanting soil and of moisture in permanent bed period. 4. According to multiple regression between yield and soil physical properties, porosity of preplanting soil was in the greatest contribution. Among aggregations, the variation in permanent bed period was in the greatest contribution.

• Journal of Ecology and Environment
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• v.32 no.4
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• pp.217-220
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• 2009

The year of 2009 marks the $200^{th}$ anniversary of Charles Darwin's birth and the 150th anniversary of the publication of his book, On the Origin of Species. Having survived the 150 years of hardening and tempering, Darwin's theory of natural selection is now more comprehensive and powerful than ever. It casts its shadow over nearly all academic disciplines and societal sectors. It truly revolutionized the way we look at the world and ourselves. In the midst of Darwinian revolution, however, Korea remains as a backward country as far as the understanding of Darwin and his theory is concerned. A variety of intellectual activities organized to celebrate the Year of Darwin is helping to narrow the gap. This article summarizes the kinds of such activities held in Korea this year and explains how Darwin made all this possible. To paraphrase the famous quotation by Theodosius Dobzhansky, I now dare to say, "Nothing in life makes sense except in the light of evolution".

• Journal of Ginseng Research
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• v.3 no.1
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• pp.35-39
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• 1979

Present studies were carried out to clarify the variation of flowering date in the variants of Korean ginseng Plants. In general, the variation of flowering date of violet-stem variant was found to be mere variable as compared with that of yellow-berry variant. And flowers began to bloom earlier in yellow-berry variant than in violet-stem variant. In violet-stem variant as well as in yellow-berry variant, the flowering date of 5-year old plants was earlier than that of 3- and 4-year old plants. As for the flowering date according to the different lines, the third line was earlier than the first or the fifth line.

• Journal of Applied Reliability
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• v.10 no.1
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• pp.57-64
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• 2010

The HANARO nuclear research reactor had been operated successfully and smoothly up to the year 2008 since its first year of instability in year 1995 just after the completion of construction. But the reliability of the reactor has been degraded from the year 2009 due to new experimental facilities such as Feul Test Loop(FTL) and Cold Neutron Source(CNS) which were installed in the HANARO plant. It turned out that these new facilities contributed unexpected stoppage of the plant. This paper describes causes of stoppage and suggestions to improve the reliability of the plant.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.296-296
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• 2017

In order to study the content variation of Quercetin and Kaempferol associated with Varieties (with thorn, without thorn), Cultivating Locations, Collecting Seasons, Leaves of Cudrania tricuspidata (carrier) Bureau containing higher content of pharmaceutical components than the other parts were tested after collecting 6 varieties including w or w/o thorn from 4 locations such as Cheongsong, Milyang, Goesan and Gochang at 3 seasons, spring, summer and fall in 2015 and 2016. As a result, Kaempferol content associated with Varieties between with thorn and without thorn, collecting Locations and Years have no difference statistically in their mean values but the differences associated with Seasons were statistically significant. The content was higher at spring and then gradually declined at summer and fall. The content variation in Year 2015 which was higher at spring and lower at summer and then recovered at fall abnormally, shows similar pattern of sunshine variation of the year. The content variation of Quercetin and Kaempferol seems to be come from climate fluctuation specially in Sunshine hours rather than Varieties, Locations. The variation associated with drying methods for utilizing leaves are statically significant. Natural Dry was shown the least variation because heat input while drying makes degradation of the content.

• Ocean and Polar Research
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• v.43 no.1
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• pp.31-43
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• 2021

To understand the temporal variation of prokaryotic communities in a temperate coastal area, prokaryotic abundance, activity, and community composition were investigated every week for over a year at a coastal monitoring station of Yeong-do, Busan. The prokaryotic abundances fluctuated about 10 times, ranging from 2.0 to 20.1 × 10⁵ cells mL^-1 and tended to be high in spring when phytoplankton bloom occurred. The prokaryotic thymidine incorporation rates (TTI) varied in a low range between 0.2 and 11.5 pmol L^-1 h^-1 in winter. However, in summer, TTI were increased up to a range of 8.3 to 17.4 pmol L^-1 h^-1, showing an increasing pattern in summer. During the study period, Alphaproteobacteria was the most dominant class for most of the year, followed by Flavobacteria. While the seasonal variation of prokaryotic composition was not apparent at the class level, many prokaryotic species showed a distinct temporal or seasonal variation for the year. In the coastal site, prokaryotic biomass and activity did not show significant correlations with temperature and chlorophyll-a, which are well known to regulate prokaryotic growth in marine environments, suggesting that the study area may be affected by diverse sources of organic matter for their growth.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.2
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• pp.231-245
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• 2003

Hourly PM$_{10}$ concentrations measured at 11 sites in Seoul and 10 sites in the large cities over South Korea for the period from March 1995 to February 2000 are analyzed to examine annual trend and monthly variations of the PM$_{10}$ concentrations. Further analysis has been carried out by using the one year data from March 1999 to February 2000 to see the seasonal variation, diurnal variation and weekly variation of the seasonally averaged PM$_{10}$ concentrations at each site. Weekly variations of the CO concentrations at the same sites for the same one year period are compared with that of the PM$_{10}$ concentration. There is no significant annual trend in the variation of the PM$_{10}$ concentration at all the sites analyzed. The seasonal and monthly mean concentrations show a minimum concentration in summer and alternative maximum concentration in spring and winter for most sites. The diurnal variation of the seasonally averaged mean PM$_{10}$ concentrations is strongly affected by traffic loads and meteorological conditions. The weekly variation of seasonal averaged concentrations of CO and PM$_{10}$ shows a high concentration for weekdays in spring, autumn and winter while high concentration for weekends in summer.nds in summer.

• Applied Biological Chemistry
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• v.24 no.4
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• pp.230-237
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• 1981

For the investigation of efficient use of fertilizer nitrogen NPK simple trials were carried out using newly bred Tongil line(japonica indica hybrid selection) and the leading local varieties with sulfur coated area in fields for two years. The yield of Tongil line was higher than that of leading local varieties by 16% in the cool year and 23% is warm year with high solar radiation from NPK simple trials including SCU and 2-split application which were carried in 130 fields at 32 locations. Warm year increased yield by 9% in Tongil but only 3% in the local than the cool year did. Optimum nitrogen level was higher in Tongil by 3.8㎏ in the cool year and 5.5㎏ in warm year than for the local. Yearly variation of optimum nitrogen in the carne variety was greater than varietal variation in the same Year. Two-split application resulted in 1 to 2% of inconsistent yield variation. Sulfur coated urea increased yield by average 2 to 4% even at 20% reduced rate of nitrogen. It was remarkably effective in same $(27{\sim}39%)$, virgin (20%) and unmatured (10%) soils.