• Membrane and Water Treatment
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• 제15권3호
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• pp.99-106
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• 2024

This study developed an efficient management plan to improve the water quality by analyzing fluctuations in the ratio and amount of various organic substances in streams considering watershed characteristics and rainfall patterns. Monitoring was conducted on three streams and one lake over seven sessions during wet and dry seasons. Water quality indicators including total organic (TOC), refractory dissolved organic (RDOC), and particulate organic (POC) carbons were analyzed using high-temperature combustion oxidation. The three streams (Cheongmi, Yanghwa, and Bokha) displayed high TOC concentrations during the rainy season because the accumulated organic substances from the dry season were washed away by rainfall. By contrast, Paldang Lake exhibited a substantial decrease in TOC concentration due to dilution, which was influenced by watershed and rainfall characteristics. Across all streams and lakes, dissolved organic carbon (DOC) accounted for the highest proportion, at 77.5% of TOC, with RDOC making up 91% of DOC and 71% of TOC. Although POC contributed a small annual proportion to annual TOC, the concentration rapidly increased during late spring and early summer, with increases of 40.403%, 25.99%, and 27.388% in Cheongmi, Yanghwa, and Bokha, respectively. Continuous monitoring of RDOC is essential to identify seasonal fluctuations and changes due to rainfall events. Furthermore, intensive POC management during the rainy season, particularly in May and June, is potentially economical and efficient for water quality management.

• The Korean Journal of Ecology
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• 제26권4호
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• pp.181-188
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• 2003

남한산성 지역에서 1999년부터 2000년까지 2년 동안 춘계단명식물의 생육특성을 밝히기 위해 현호색속의 Pes-gallinaceua절에 속하는 집단에서 괴경을 중심으로 생육기 동안 생장특성을 조사 분석하였다. 그 결과 생육초기 괴경에서 지상부의 발생은 토양의 해빙에 따라 일어났으며 토양의 깊이가 깊을수록 지상부의 출현시기가 늦었다. 현호색은 3월 하순에 지상부가 출현하고 5월 초순에 고사하여 총 생육기간은 평균 45일 정도 이었다. 현호색 집단에서 괴경과 총 건중량에 의한 개체의 크기별 빈도는 최소계급이 가장 높았으며(총 건중량에서 40%, 괴경의 건중량에서 53%)중간계급 이하의 빈도는 전체의 93(총 건중량)∼96%(괴경의 건중량)을 나타내 작은 개체가 대부분을 차지하는 개체군으로 나타났다. 괴경은 생육초기 지상부가 출현하여 일이 완전히 전개되기 전까지 비중이 0.14까지 감소하였다가 생육기 말 종자가 결실하고 지상부가 고사하는 시기에 0.42까지 증가하였다가 이 후에 다시 서서히 감소하였다. 한편, 생식기관이 있는 것은 없는 것에 비하여 생육기간 동안 괴경의 비중이 낮았으며 1% 이하에서 유의한 차이를 보였다. 생육기말 괴경의 부피에 따른 괴경의 비중은 감소하였고 엽면적은 대체로 증가하였으나 경향성이 뚜렷하지 않았으며 지상부/지하부의 비율은 일정한 경향성이 없었다. 한편, 괴경의 건중량이 증가할수록 괴경의 비중은 감소하였고 엽면적은 증가하였으며 증가 혹은 감소하는 경향성은 뚜렷하였다. 작은 개체일수록 괴경에 많은 양의 에너지를 축적하였으며 지상부/지하부의 비율은 개체마다 다양한 것으로 나타났다.

• 한국수정란이식학회지
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• 제27권2호
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• pp.87-92
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• 2012

A study on estrus synchronized dairy cows using progesterone intravaginal device was done to classify each cow's reproductive status from calving to synchronization and to evaluate the reproductive performance according to ovarian and uterine status, and calving season. From calving to estrus synchronization, silent heat or error of estrus detection among ovarian status and endometritis among uterine disorders were exposed in the most distribution (75.4% and 48.3%, respectively). The pregnancy rate of cows with inactive ovaries was lower than those in the follicular and luteal phase. And according to the uterine status before estrus synchronization, the pregnancy rate was similar in three groups; normal, endometritis, and pyometra (70.9, 69.1 and 100%, respectively). The interval from calving to conception was shorter (p<0.05) in cows calved during autumn than in cows calved during spring and winter.

• Asian-Australasian Journal of Animal Sciences
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• 제5권3호
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• pp.475-480
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• 1992

The effect of mechanical factors and season of the year on milking characteristics (milk yield, time of milking, rate of milk flow, stripping time and tripping milk) were studied on 26 Holstein Friesian cows, raised under Saudi Arabia environmental conditions. Cows were in the third and fourth lactation and reached the peak. Cows milked twice a day with equal intervals. Three vacuum levels (34, 38 and 42 cfm) and two pulsation ratios were used to form six vacuum-pulsation combinations. The study was carried during two seasons Autumn-Winter (S1) and Spring-Summer (S2). After absorbing the cow equations least square analysis was used to analyze the data. Vacuum level 38 cfm and pulsation ratio 70:30 was the best among all combinations of vacuum level-pulsation ratio. No significant effect (p < .01) for season, up to the seventh half minute, on the rate of milk flow. However, season of the year has a significant effect on total milk yield, stripping time and stripping milk.

• Fisheries and Aquatic Sciences
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• 제6권4호
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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.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2000년도 춘계 학술대회지
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• pp.204-205
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• 2000

• 한국농공학회:학술대회논문집
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• 한국농공학회 2001년도 학술발표회 발표논문집
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• pp.484-487
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• 2001

Runoff, sediments and nutrient losses were studied under different patterns of paddy field management: (1) fall and spring plowing (PL); (2) fall plowing for half of plot and spring plowing (SPL); (3) no-till for fall and spring plowing (NPL) during the non-cropping period in the southern Korea. Sediment losses from PL plot were 25% more than those from NPL plot. There was significant difference in nutrient losses via runoff water and sediment according to plowing practice (P < 0.01). Losses of total-N, ammonia-N, nitrate-N, total-P from NPL plot were larger than PL and SPL plots during study period. Sediment and total-P losses from SPL plot were close to those of PL plot.

• 한국산림과학회지
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• 제9권1호
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• pp.45-48
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• 1969

야외 피해림지에서 봄철의 솔잎혹파리 유충밀도의 감소경향을 조사한것이다. (1) 해빙직후인 3월 12일의 유충수를 100으로 보았을 때 4월 15일은 29, 5월 4일에는 10 이하 이였다. (2) 봄철에 시기에 따라서 유충수가 점점 감소되는 것은 온도가 차차 높아지고 습도가 낮아 지는것이 큰 원인이라고 관찰되었다. (3) 지표토양에서 솔잎혹파리 유충을 선별 함에는 수선하는 방법이 가장 좋았다.

• 수산해양기술연구
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• 제60권1호
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• pp.37-46
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• 2024

This study was conducted to provide the basic information on environment effects on appearance of ichthyoplankton in the Yeongsan River Estuary in Spring and Summer from 2018 to 2020. Data were obtain from the database of 'Coastal Ecosystem' in "National Survey of Marine Ecosystem." Among the abundance ichthyoplankton species, the Gobiidae spp. dominated, accounting for 85% of the total abundances with the secondary dominant species being the Parablennius yatabei, representing 3% of the abundances. Cluster analysis results revealed a composition differentiated between spring and summer. The Yeongsan River Estuary is known to be significantly influenced by the opening and closing of estuarine gates. In this study, the fluctuation in the number of occurrence groups and abundance among the years and season is attributed to the phenomenon of high water temperature period and the freshwater discharge.

• 농업생명과학연구
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• 제46권6호
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• pp.51-57
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• 2012

본 연구는 안개를 채취하여 화학적 조성을 분석하고 금후 산성안개의 대책에 필요한 기초자료로 활용하고자 수행하였다. 안개수의 pH는 2010년도가 4.3이었고, 2011년은 4.0으로서 강한 산성이었고, 전기전도도는 평균 477.2와 $562.7{\mu}s$이었다. 안개수의 음이온 중 봄철과 여름철 $NO_3{^-}$ 농도가 각각 267.1, 279.1 mg/L로서 가장 높았고, 다음으로 $SO{_4}^{2-}$ 농도가 각각 177.2, 198.6 mg/L이었다. 가을과 겨울철 $NO_3{^-}$ 농도가 각각 217.7, 237.9 mg/L로서 가장 높았고, 다음으로 $SO{_4}^{2-}$농도가 각각 164.2, 190.1 mg/L이었다(p<0.05). 양이온은 봄철과 여름철 $Ca^{2+}$농도가 각각 221.3, 233.7 mg/L로서 가장 높았고, $Na^+$ 농도가 각각 125.1, 131.7 mg/L이었다. 가을과 겨울철에 $Ca^{2+}$농도가 각각 196.8, 198.8 mg/L로서 가장 높았고, 다음으로 $Na^+$ 농도가 각각 97.1, 117.2 mg/L이었다(p<0.05). 산성안개를 일으키는 안개수의 pH와 $EC(r=-0.9861^{**})$, $NO_3{^-}(r=-0.9677^{**})$, $SO{_4}^{2-}$ ($r=-0.9510^{**}$), $Ca^{2+}$는 1% 수준에서 상관이 있었다. 산성안개수의 생성에 영향을 하는 인자의 회귀 방정식을 나타내면 $Y(pH)=6.4627+0.9723X_2(EC)+0.9364X_4(NO_3{^-})+0.9044X_5(SO{_4}^{2-})+0.8049X_{10}(Ca^{2+})+0.6709X_8(K^+)\;(r^2=0.8787)$로 추정되었다.