• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.3
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• pp.475-482
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• 2019

Over 3,200 large baleen whales including 3,173 fin whales, 7 blue whales and 28 humpback whales were hunted by Japanese whaling companies in the Yellow Sea during Japanese colonial period (1916~1944). As a result, these large baleen whales are under the endangered state in the Yellow Sea. The Yellow Sea had good living conditions for large baleen whales in the water temperature ($4{\sim}26^{\circ}C$) and food supply. The whaling on the large baleen whales was carried out mainly from early winter to late spring. The possibility of large scale whaling was caused by the migration of these baleen whales from other areas for the feeding on abundances of Euphausia pacifica in the surface layer during these seasons. During summer and autumn season, the baleen whales moved to other areas (good feeding ground as Woolsan offshore waters), because Euphausia pacifica stayed below the strong themocline which was formed from June to October in the Yellow Sea.

• Journal of The Korean Society of Grassland and Forage Science
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• v.39 no.3
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• pp.121-126
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• 2019

This experiment was conducted to breed a very early maturing variety of Italian ryegrass (Lolium multiflorum Lam.) in Grassland and Forage Crops Division, National Institute of Animal Science, RDA, Cheonan 2015-2017. The new variety of Italian ryegrass, 'Green call 2ho' is a diploid variety with green in leaf color and has semi-erect growth habit in late autumn and erect growth habit in early spring, 'Green call 2ho' was in heading date as a early-maturing variety April 24. Also 'Green call 2ho' was narrower by 2 mm in flag leaf width, longer by 2.5 cm in flag leaf length and shorter by 3 cm in plant height than those of the control variety, 'Florida 80', respectively. 'Green call 2ho' was also thicker by 0.33 mm in stem thickness and strong in winter hardness. Dry matter (DM) yield (11,688 kg/ha) of 'Green call 2ho' was 7% higher than that of 'Florida 80'. Total digestible nutrient (TDN), crude protein (CP) and relative feed value (RFV) of 'Green call 2ho' were 61.3 %, 9.8 % and 98.2, respectively which are 2.6, 0.6, and 8.4 % higher, respectively than those of 'Florida 80', respectively. Acid detergent fiber (ADF) and neutral detergent fiber (NDF) of 'Green call 2ho' were 34.9 and 58.5 % which are 3.3 and 2.7 % lower than those of 'Florida 80', respectively.

• Development and Reproduction
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• v.27 no.3
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• pp.101-115
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• 2023

Environmental factors impact oyster growth, condition, and gonadal development, which is linked to gamete characteristics observed through histology. The reproductive cycle of bivalves is related to energy storage and utilization. Therefore, in this study, the year-round growth change and gonadal development of oysters were observed using histological analysis, and the biochemical composition changes were confirmed. The oysters used in this study are being nurtured in Gadeok-do, and 40 oysters were randomly sampled monthly from March 2021 to February 2022. Result of histological analysis of gonads, oysters were showed early development from December to February, late development from March and April, mature and ripe from May to July, spawned from August to October, and spent from November to December. Condition index values of oysters decreased in summer and autumn and increased again when entered the spent after spawning. The protein content of oysters was high in May, the maturity period, and the lipid content decreased during the spawning period. In addition, EPA and DHA, the major fatty acids of oysters, were low during the spawning period and high during the maturation period. As a result, this study suggested a close relationship between changes in oyster growth, biochemical composition, and the reproductive cycle.

• Journal of Korean Society of Forest Science
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• v.98 no.6
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• pp.748-756
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• 2009

The key for cultivating Lentinula edodes in sawdust bags with an appropriate strain and medium is to encourage the mushroom growth, while discouraging contaminating fungi by controlling environment, especially temperature and relative humidity (RH). To investigate the daily and seasonal fluctuation of temperature and RH in two L. edodes cultivation sheds types, HOBO data loggers was set and the collected data were analyzed. In a Taiwan type L. edodes cultivation shed, temperature and humidity changes were divided into five characteristic periods: mycelium growing winter, mushroom fruiting spring, mushroom fruiting early summer, mushroom nonfruiting summer and mushroom fruiting autumn. First, the mycelium growing winter was December to early March with daily mean temperature of $-1{\sim}8^{\circ}C$. Second, mushroom fruiting spring was mid March to late May with daily mean temperature of $8{\sim}21^{\circ}C$ and day-night temperature difference of $15^{\circ}C$. Third, the Mushroom fruiting early summer was early June to early July with 17 to $25^{\circ}C$. Fourth, nonfruiting summer was mid July to mid August with daily mean temperature of $25{\sim}28^{\circ}C$. Lastly, mushroom fruiting autumn was late August to October with daily mean temperature of $10{\sim}23^{\circ}C$ and with cyclic temperature change by $7^{\circ}C$ decrease and 5 increase every 5 to 7 days. In a Chinese type shed, temperature ranged $-1.9{\sim}5.0^{\circ}C$ during winter and $15{\sim}32^{\circ}C$ during June to October. Temperature and relative humidity changed $12{\sim}30^{\circ}C$ and 40~100%, respectively, depending on 0~150 cm shelf heights of by positions in the shed. In conclusion, to grow L. edodes but to discourage contaminating fungi, that is, not to be too high in temperature and RH, the growers changed temperature and RH by adjusting shading, aeration and insulation in the shed.

• 한국해양학회지
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• v.30 no.5
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• pp.403-412
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• 1995

The present study was performed to determine th growth and production of Mactra veneriformis on the Songdo tidal flat off Inchon. west coast of Korea. Monthly samples were collected from Marc 1989 to September 1990. The size distributions of shell length showed unimodal patterns from March to August 1989. The binodal pattern after September 1989 indicated a recruitment of young clams during this period. The density fluctuated irregularly, but showed a decreasing pattern over time on the whole. The density of the year class 1989 increased markedly after February 1990. The growth in shell length showed three phases during a year, a fast growth phase in spring, a slow growth phase in summer and autumn, and a lag phase in winter. The annual increment in shell length reduced with age. The flesh dry weight showed a peak in late spring just before the spawning period, and another peak in autumn. The length of annuli and the back-calculated flesh dry weight were used to describe the annual growth. The growth in shell length fitted to the von Bertalanffy model and the flesh dry weight to the Gompertz model. The absolute growth rate of the shell length reduced gradually with age. The year class 1985 had the highest L, and the yeat class 1986 the lowest L. The annual growth in weight showed a typical sigmoid curve. The growth rate was maximum at the age of 2 to 3. Year classes of 1984 and 1985 had higher values of W and higher absolute growth rates than those of 1986 and 1987. Maximum absolute growth rates of 1986 and 1987 year classes were recorded at younger ages than 1984 and 1985 year classes. The annual relative growth rates of length and weight decreased exponentially with age. Biomass in flesh dry weight increased till spring and thereafter decreased progressively. Maximum biomass was 134.6g m/SUP -2/ in August 1990. The biomass of 1989 yeat class occupied highest proportion in total biomass. Annual production in flesh dry weight from March 1989 to March 1990 was 67.9 g m/SUP -2/ year/SUP -1/. Cumulative production of 1989 year class was highest among all year classes, and that of year class 1984 was lowest. The production is high in spring and autumn, and very low in summer and winter.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.5
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• pp.695-706
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• 1998

SST (Sea Surface. Temperature) fronts which were found in the South-West Sea of Korea and the northern area of the East China Sea were examined in order to clarify their positions, shapes, seasonal changes and the formation mechanism, For this study used SST data rearranged from the SST IR image during 1991 to 1996 and oceanographical data obtained by National Fisheries Research and Development Institute. Temperature front in the Cheju Strait was analyzed by the data obtained from a fisheries guidance ship of Cheju Provincial Government, The coastal frontal zone in the South-West Sea of Korea and the offshore frontal zone in the northern area of the East China Sea can be divided into several types (Type of Winter, Summer, Spring, Autumn and late Autumn), Short term variations of SST fronts have a tendency not to move to any Bleat extent for several days. The location of the frontal zone in the southwestern sea of Cheju Island changes on a much large scale than that of the one in the southern coast of Korea, The frontal Tone, formed every year in the southern sea of Korea approaches closer to the coastal area in winter, and moves closer to the south in spring and autumn. The frontal zone of the southwestern sea of Cheju Island moves in a westerly direction from the east, and reaches its most westerly point in the winter and its most easterly point in the summer related to the seasonal change of the Tsushima Current. Additionally, the frontal zone of the southwestern sea of Korea becomes extremely weak in March, April and November. SST fronts are formed every year around the line connecting Cheju Island to Yeoseo Island or to Chungsan Island in the Cheju Strait. A Ring-shaped tidal mixing front appears along the coastal area of Cheju Island throughout the year except during the months from November to January. Especially, in May and October fronts are formed between the coastal waters of Cheju Island and the Tsushima currents connecting the frontal zone of the coastal region in the southern sea of Korea with that of the southwestern sea of Cheju Island.

• Journal of The Korean Society of Grassland and Forage Science
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• v.4 no.3
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• pp.206-211
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• 1984

The influence of fertilizer on the growth characteristics in Korean lawn grass was studied from June through October in a experiment. The results were as follows: 1. Maximum dry matter weight of Korean lawn grass was achieved in early in early August when it was $64.3g/m^2$ without fertilizer and $157.9g/m^2$ with fertilizer. On the other hand, the dry matter weight of whole plant including Korean lawn grass reached the maximum in late September, which was late, to some extent, compared with that if pure Korean lawn grass, presumably associated with seed maturing period of $C_4$ type plants. 2. Notable positive effect on leaf blade and non-leaf part weight in Korean lawn grass was also detected. However, the rate of dry matter occupied by non-leaf part was markedly increased by fertilizer application. 3. The dry matter portion occupied by Korean lawn grass the in total dry matter weight of whole plant was significantly decreased as time went by, particularly in case of fertilizer application. 4. Fertilizer, which might imply an increased potential of tiller numbers according to fertilizer. 5. In general, the seasonal change pattern of the rhizome of Korean lawn grass coincided with that of the aboveground organs: Its maximum dry matter weight achieved from late August to early September was $194.2g/m^2$ with nil fertilizer, and, with fertilizer, $259.7g/m^2$, of which figures were equivalent to be increased to 33.7%, compared to that with nil fertilizer. Applying fertilizer increased the weight of root: The highest values were $36.7g/m^2$ with nil fertilizer and $80.9g/m^2$ with fertilizer.

• Journal of The Korean Society of Grassland and Forage Science
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• v.36 no.4
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• pp.287-292
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• 2016

The objective of this study was to determine the effect of harvesting time of rice on growth characteristics and dry matter yields of Italian ryegrass (Lolium multiflorum Lam., IRG) 'Kowinearly' after seeding them in paddy field. Experiments were performed in National Institute of Animal Science, RDA (Cheonan, Choongcheongnam-do province of Korea) for four years (2011~2014). Italian ryegrass variety 'Kowinearly' was seeded at experimental paddy fields before rice harvest in late September. Rice were harvested at 10, 20, and 30 days after seeding of IRG. As the harvest time of rice became later, the number of tillering before winter was reduced and IRG plant length before winter was shorter. The dry matter yield of IRG was also reduced. When rice were harvested at 20 days and 30 days after sowing of IRG compared to the rice harvested in autumn at 10 days after sowing of IRG, the number of tillering for IRG before winter was decreased by an average of 19% and 40%, respectively. The winter survival ratio of IRG was decreased by an average of 13% and 19%, respectively. Their dry matter yields were also reduced by an average of 8% and 19%, respectively. The heading date was different from each other in three years. The plant length at the time of IRG harvest in the spring was not significantly different among treatment groups. Taken together, our results suggest that when Italian ryegrass is grown in paddy fields by the method of 'seeding of IRG before rice harvest', rice should be harvested as soon as possible after sowing of IRG 'Kowinearly' in the autumn to increase forage productivity.

• Journal of Environmental Impact Assessment
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• v.26 no.2
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• pp.127-139
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• 2017

Measurements of net ecosystem exchange (NEE) of $CO_2$ based on the eddy covariance technique provide reasonable carbon balance estimates in response to local environmental conditions. In South Korea, the forest ecosystems cover approximately 64% of the total area, thereby strongly affecting regional carbon balances. Cultivated croplands that cover about 17% of the total area should also be considered when calculating the carbon balance of the country. In this study, our objectives were (a) to quantify the range and seasonal variation of NEE at forest ecosystems, including deciduous, coniferous, and mixed forests, and agricultural ecosystems, including rice paddies and a potato field, in South Korea and (b) to compare NEE at ten Fluxnet sites that have the same or similar ecosystems as found in South Korea. The results showed that the forest and agricultural ecosystems were carbon sinks. In Korea, NEE at the forest ecosystems varied between -31 and $-362gC/m^2/yr$, and NEE at the croplands ranged from -210 to $-248gC/m^2/growing$ season. At the deciduous forest, NEE reached low values in late spring, early summer, and early autumn, while at the coniferous forest, it reached low values in spring, early summer, and mid autumn. The young mixed forest was a much stronger carbon sink than the old-growth deciduous and coniferous forests. During each crop growing season, beet had the lowest NEE value within six crops, followed by wither wheat, maize, rice, potato, and soybean. These results will be useful for designing and applying management strategies for the reduction of $CO_2$ emissions.

• Korean journal of applied entomology
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• v.46 no.1 s.145
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• pp.71-78
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• 2007

Biological control of Liriomyza trifolii (Burgess) using Diglyphus isaea (Walker) has been evaluated in tomato greenhouse, for three seasonal culture types: spring type (March-July), summer type (June-October) and autumn type (July-December). For spring type, totally 5.8 $individuals/m^2$ of D. isaea has been released at six times from late April, when the density of L. trifolii was about 1.0 individuals/plant. Corrected mortality of Liriomyza trifolii caused by parasitoids was 97.6% at early July, and the proportion of D. isaea was 88.9% of all parasitoids collected in the greenhouse. In the case of summer type, totally 1.8 $individuals/m^2$ of D. isaea has been released at five times from early July, when the density of 1. trifolii was about 0.4 individuals/plant. Corrected mortality of L. trifolii caused by parasitoids was 84.4% during the whole season, but the proportion of D. isaea was very low (only 13.8%). Immigrating parasitoids such as Chrysocharis penthus were synchronized to control the leafminer in the greenhouse. For autumn type, totally 2.7$individuals/m^2$ of D. isaea has been released at four times from mid September, when the density of L. trifolii was about 0.7 individuals/plant. Corrected mortality of f. trifolii caused by parasitoids was 85.7% at mid December, and the proportion of the D. isaea was 83.4%.