• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.5
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• pp.517-532
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• 1995

Distribution of zooplankton was studied based on the zooplankton samples from collected 15 stations in Deukryang Bay in July and September, 1992 and January and March, 1993. Zooplankton biomass $(mg/m^3)$ showed maximum in March and minimum in July, whereas abundance $(inds./m^3)$. showed maximum in September and minimum in March. Variation in biomass depended on changes in body size of Sagitta crassa. S. crassa of large body size resulted in high biomass in March. Noctiluca scintillans and copepods in September showed high abundance but low biomass. Species composition and abundance were closely related to seasonal variation of water temperature. Of the dominant zooplankton taxa, decapod larvae were predominant in July, copepods in September and January, and coelenterates 3n March. Three copepod species, Paracalanus indicus, Acartia pacifica and Pseudodiaptomus marinus were dominant in July and March, September, and January, respectively.

• Journal of Aquaculture
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• v.11 no.4
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• pp.475-485
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• 1998

To clarify annual reproductive cycle of Koran dark sleeper, odontobutis platycephala, we examined the seasonal changes of gonadosomatic index(GSI), testicular development stages and sex steroid hormones in blood from December 1995 to November 1997. Testis was podlike shape from July to October, and tadpole-like shape from November because of its expanded posterior part. GSI was 0.14~0.18 from July to September and increased to $0.43{\pm}0.04$ in October and then was not changed significantly until February. GSI was reincreased to $0.52{\pm}0.09$ from March and then was kept at similer levels until May, but fell down to $0.28{\pm}0.05$ in June. As results of histological observation, testis was divided into 3 parts(anterior, boundary, posterior) in the development progress of germ cells. In July, the testis was composed of only spermatogonia without seminiferous tubules in most fishes. In the anterior part of testis, the ferquency of spermatogenesis stage seminiferous tubules appearing in August was more than 80% from September to December. decreased gradually from January to March and drastically in April, and then disappeared in June. The frequency of spermiogenesis stage seminiferous tubules appearing in December, increased gradually from January to March and drastically to 80% in April, and reached to 90% the highest levels of the year in June. Post-spawning stage seminiferous tubules did not appear throughout the year. The frequency of spermatogonia was 100% and 65% in July and August, and less than 20% in the rest period of the year. In the boundary part, the frequency of spermatogenesis stage seminiferous tubules appearing in August increased from September and reached to 82% in November, decreased from December, adn disappeared in March. The frequency of spermiogenesis stage seminiferous tubules appearing in November was less than 18% until February, and increased to 29%~57% from March to June. The frequency of post-spawning stage seminiferous tubules appeared 12%~25% only from March to June. The frequency of spermatogonia was 100% in July, decreased to 85% in August and 10% in November, and increased gradually from December to 50% in April, and decreased again from May to June. In the posterior part, seminiferous tubules with some seminiferous tubules increased drastically 80%~85% in August and September, decreased drastically from October to November and remained below 10% until February, and disappeared after March. The frequency of spermiogenesis stage seminiferous tubules appearing in August increased sharply from October and reached to 75% in November. decreased to 15% in December and no significant changes until March, and disappeared after April. The frequency of post-spawning stage seminiferous tubules appearing very early in November increased to 82% in December and 85%~95% until June. The frequency of spermatogonia was 100% in July, decreased drastically to 15% in August, disappeared from October to Mrch, but reappeared from April and kept at less than 10% until June. The blood level of testosterone (T) increrased gradually from August was $0.61{\pm}0.09 ng/m\ell$ in November, increrased drastically to $3.99{\pm}1.22 ng/m\ell$ in December and maintained at in similar level until March, and decreased to $0.25{\pm}0.14 ng/m{\ell} ~ 0.17{\pm}0.13ng/m{\ell}$ in April and May and no significant changes until July (P<0.05). The blood level of 17, 20 -dihydroxy-4-pregnen-3-one $ng/m{\ell}$in the rest of year without significant changes(P<0.05). Taken together these results, the germ cell development of testis progressed in the order of posterior, boundary, anterior part during annual reproductive cycle in Korean dark sleeper. The testicular cycle of Korean dark sleeper was as follows. The anterior part of testis : i.e. spermatogonial proliferation period (July), early maturation period (from August to November), mid maturation period (from December to March), late maturation period (from April to May) and functional maturation period (June) were elucidated. The boundary of testis, i.e. spermatogonial proliferation period (July), early maturation period (from August to October), mid maturation period (from November to February) and the coexistence period of late maturation, functional maturation and post-spawn (from March to June) were elucidated. The posterior of testis, i.e. spermatogonial proliferation period (July), mid maturation period (from August ot September), late maturation period (October), functional maturation period (November) and post-spawn period (from December to June) were elucidated. It was showed that the changes of sex steroid hormone in blood played a important roles in the annual reproductive cycle of Korean dark sleeper.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.2
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• pp.83-94
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• 2010

The objective of this study was to determine the best probability distributions of annual, seasonal and monthly precipitation in Korea. Data observed at 32 stations in Korea were analyzed using the L-moment ratio diagram and the average weighted distance (AWD) to identify the best probability distributions of each precipitation. The probability distribution was best represented by 3-parameter Weibull distribution (W3) for the annual precipitation, 3-parameter lognormal distribution (LN3) for spring and autumn seasons, and generalized extreme value distribution (GEV) for summer and winter seasons. The best probability distribution models for monthly precipitation were LN3 for January, W3 for February and July, 2-parameter Weibull distribution (W2) for March, generalized Pareto distribution (GPA) for April, September, October and November, GEV for May and June, and log-Pearson type III (LP3) for August and December. However, from the goodness-of-fit test for the best probability distributions of the best fit, GPA for April, September, October and November, and LN3 for January showed considerably high reject rates due to computational errors in estimation of the probability distribution parameters and relatively higher AWD values. Meanwhile, analyses using data from 55 stations including additional 23 stations indicated insignificant differences to those using original data. Further studies using more long-term data are needed to identify more optimal probability distributions for each precipitation.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2022.09a
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• pp.82-82
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• 2022

천마(天麻, Gastrodia elata Blume)는 난초과(蘭草科, Orchidaceae)에 속하는 식물로 잎과 뿌리가 없어 탄소동화능력이 없으며, 뽕나무버섯균과 공생하는 기생식물이다. 주요 함유된 성분은 gastrodin, 4-hydroxylbenzyl alcohol, vanillin, vanillyl alcohol, ergothioneine 등이 있고, 주로 진정(鎭靜), 진경(鎭痙), 통락(通絡)의 효능이 있으며, 두통, 반신불수, 언어장애, 현훈(眩暈), 고혈압 등에 사용되고 있다. 천마는 노지 재배에 따른 안정생산 문제가 지속적으로 발생하고 있다. 혹한, 폭우 등 기상환경에 따른 연차간 수량성 차가 673~1,175kg/10a로 크고, 정식 후 원목·종균·자마의 공생관계 형성이 늦어져 자마 생존율이 70% 이하로 낮으며, 18개월 장기 재배 시 생육 환경이 불량해져 썩음병이 많이 발생하고 있다. 본 연구는 비가림시설, 종균 선(先) 접종 배양목 및 20g 이상의 자마를 사용하여 재배기간을 18개월에서 12개월로 6개월을 단축하고자 수행하였다. 본 실험은 종균 선접종 배양목 생산을 위해 ^①원목의 종균 접종 시기는 4월 하순, 6월 상순, 7월 중순으로 40일 간격으로 처리하였고, 이렇게 생산된 배양목을 활용하여 정식은 이듬해 4월 상순, 수확은 그 이듬해 3월 하순으로 설정하였다. 또한, 종균 선접종 배양목을 활용한 ^②천마의 정식 시기는 3월 상순, 4월 상순, 5월 상순으로 30일 간격으로 처리하였고, 수확 시기는 이듬해 2월 하순, 3월 하순, 4월 하순으로 설정하여 천마의 생육상황 및 생산성을 조사하였다. ^①원목의 종균 접종시기를 검정한 결과, 자마 생존율은 4월 하순과 6월 상순 처리가 무처리에 비해 15%가 높았고, 천마 수량은 무처리 대비 4월 하순과 6월 상순 처리구에서 각각 2.07배, 1.64배 높았다. ^②천마의 정식 시기를 검정한 결과, 천마의 유효적산온도는 2,400℃로 3월 상순 처리구는 2,446℃로 충족하였고, 4월 중순 처리구는 2,375℃로 거의 충족하였으나, 5월 상순 처리구는 2,178℃로 222℃가 부족하였다. 자마 생존율은 3월 상순 처리 시 95%로 가장 높았고, 정식 시기가 늦어질수록 자마 생존율이 낮아지는 경향을 보였으며, 수량성은 5월 상순 처리 대비 3월 상순이 3.56배, 4월 상순이 3.43배 높았다. 따라서, 자마 생존율, 유효적산온도, 천마 수량성 등의 결과에 따라 원목의 적정 종균 접종 시기는 4월 하순과 6월 상순 사이고, 천마의 적정 정식 시기는 3월 상순과 4월 상순 사이며, 비가림시설, 종균 선접종 배양목 및 우량자마를 활용하면 재배기간을 노지 대비 6개월 이상 단축할 수 있을 것으로 판단되었다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.441-445
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• 2005

태화강 주변지역 지하수의 계절적 수질 변화를 보고자 현장측정 항목(수온, pH, 알칼리도, 전기전도도), 일반 항목(증발잔류물, 총경도, 과망간산칼륨소비량), 음이온물질$(F^-,\;Cl^-,\;{NO_3}^-,\;{SO_4}^{2-})$, 양이온물질$(Ca^{2+},\;Mg^{2+},\;K^+,\;Na^+)$등으로 구분하여 분석하였으며, 총 70개 지점을 대상으로 2004년 5월, 10월 2회에 걸쳐 실시하였다. 지역별 수질특성을 살펴보면 남구지역은 $Ca-Mg-HCO_3,\;Ca-Mg-HCO_3-Cl,\;Ca-Mg-Na-Cl-HCO_3,\;Na-Cl-HCO_3$의 4가지 유형이 전체 시료의 74%를 차지하였으며, $Ca-Mg-HCO_3$형이 가장 우세하게 나타났고, 중구지역 지하수에서는 $Ca-Mg-HCO_3-Cl,\;Ca-Mg-Na-HCO_3-Cl,\;Ca-Mg-HCO_3$의 3가지 유형이 전체 시료의 60%를 차지하는 것으로 나타났으며, 이중에서 $Ca-Mg-HCO_3-Cl$형이 가장 우세하게 나타났다. 두 지역의 수질 변화를 살펴보면. 전기전도도는 남구는 $731.5{\mu}s/m^3$에서 $529.8{\mu}s/m^3$, 중구는 $752.6{\mu}s/m^3$에서 $621.6{\mu}s/m^3$로 201.7, $131.0{\mu}s/m^3$만큼 작아져 두 지역 모두 같은 양상을 보였으나, Hardness 및 TDS의 경우 남구지역은 5월보다 10월에 평균, 최대값이 모두 낮게 나타났다. 또한 $Cl^-$의 경우 지역적, 계절적으로 큰 차이를 보이고 있으며 남구는 5월 68.2mg/l, 10월에는 61.7mg/l로 다소 감소하였으나 중구의 경우 5월 75.5mg/l, 10월 122.1mg/l로 다소 증가한 것으로 나타났다. 양이온 분포 비율 및 농도는 비슷하게 나타났으며, 계절적으로 5월보다 10월에 모두 높게 나타났다. 두 지역 모두 양이온물질 중 나트륨의 분포비율 및 농도가 5월보다 10월에 다소 높게 나타났다. 연구 지역 지하수의 계절적 수질변화를 살펴보면 두 지역간의 지하수질 및 분포특성에 있어 다소 차이를 보이고 있으며, 특히 중구 지역에서 5월보다 10월에 나트륨과 염소이온의 증가가 다소 나타나는 것으로 관찰되었다. 또한 연구지역 중 특이지점($Cl^-$:1,000mg/l이상)은 남구는 5월에 2개에서 10월에는 3개 지점으로 증가하였으며, 중구는 5월, 10월 모두 4개 지점으로 나타났다.

• Korean Journal of Environmental Agriculture
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• v.1 no.1
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• pp.31-38
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• 1982

The water quality at the Nakdong River stream was surveyed for 3 years from 1978 to 1980 at quarterly intervals of January, April, June and October at 12 sites along the main stream from Sangju to Imhaejin and at 2 sites of Geumho and Nam River tributaries. The overall results are summarized as follows: 1) The levels of dissolved oxygen in the Geumho River tributary on the basis of three-year average were 0.7 ppm in January, 1.3 ppm in April, 4.0 ppm in July and 0.8 ppm in October. BOD concentrations in the same period were 91 ppm in January, 37 ppm in April, 6 ppm in July and 24 ppm in October. The water of Geumho River was so highly contaminated that the water seems to be unsuitable for any type of water use. 2) The relatively clean water in the upstream of the main Nakdong River was rapidly polluted by the highly contaminated water of Geumho tributary. That is, dissolved oxygen and BOD at Hwawon site right after junction of the tributary were 10.4, 8.8 ppm in January, 5.8, 6.5 ppm in April, 6.3, 3.2 ppm in July and 7.0, 5.3 ppm in October, respectively. The values of turbidity, ammoniacal nitrogen and electrical conductivity were also observed to be quite high.

• Development and Reproduction
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• v.4 no.2
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• pp.175-180
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• 2000

The reproductive cycle of ovoviviparous melania snail, Semisulcospira libeytina libertina was studied in the valley near Naewon Temple in Yangsan, Korea. Water temperature (WT) of the habitat ranged from 1.3$^{\circ}C$ to 22.5$^{\circ}C$ The meat weight rate (MWR) reached the maximum with the beginning of WT increase in March and the minimum in August. Monthly changes in average oocyte diameter showed the maximum (249.6$\pm$2.6 ${\mu}{\textrm}{m}$) in July and the minimum (134.3$\pm$2.8 ${\mu}{\textrm}{m}$) in December S. libertina libertina seemed to be a year-round breeder except for mid-summer and mid-winter. Two main reproductive cycle of the species could be divided into five successive stages: multiplicative (March, October), growing (April and May, November), mature (June and July, December), ovulation (August, January), parturition (September and October, March to May) and resting (September, February) stages in female and multiplicative (March, October), growing (April, November), mature (March to June, December), copulatory (July and August, January), resting (September, February) stages in male.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.04a
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• pp.34-34
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• 2018

본 연구는 예산지역에서 현지외보전을 하는 매실나무(220여점) 및 살구나무(9점) 유전자원에 대한 개화 특성평가를 위하여 개화기를 지난 만개기를 연차별로 조사하였다. 대한민국에서 수집한 매실나무의 만개기는 이식 초기의 2012년에 4월 중순이었으나 이식 3년 후부터 4월 초순으로 약간 앞당겨졌다. 만개기는 2012년의 경우 모두 4월 11일 이후이었으나 2015년 이후는 4월 1~10일까지 70% 이상이었다. 연도별 보면 2015년과 2016년은 4월 1~5일에 가장 많이 만개하였고, 2017년과 2018년은 4월 6~10일에 가장 많이 만개하였다. 또한 일본에서 수집한 매실나무의 만개기도 대한민국 수집의 자원처럼 4월 초순이 대부분이었는데, 연도별로는 2015년, 2016년 및 2017년의 경우 4월 1~5일에 가장 많이 만개하였고, 2018년은 4월 6~10일에 가장 많이 만개하였다. 그러나 일본 수집의 매실나무 만개기는 3월말에서 4월 초순에 집중되어 3월 중순에서 4월 중순까지의 범위를 나타낸 대한민국 수집 자원과 약간의 차이를 보였다. 그리고 예산지역 현지외보전 살구나무(대한민국 수집)의 만개기는 2015년부터 2018년까지 모두 4월 1일부터 10일까지이었으며, 3월 및 4월 중순 이후에 만개한 꽃이 나타나지 않았다.

• Journal of The Korean Society of Grassland and Forage Science
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• v.40 no.1
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• pp.50-56
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• 2020

The field experiment was carried out to evaluate changes of dry matter productivity and feed value of Italian ryegrass and triticale at different growth stages in Wonju from 2018 to 2019. Italian ryegrass and triticale forages were harvested at an interval of seven days from May to June. The dry matter yield of Italian ryegrass with 7,870 kg/ha harvested on May 16 was significantly higher than that harvested on May 3 and May 9. The dry matter yield of triticale with 12,050 kg/ha harvested on June 7 was significantly higher than that harvested from May 3 to May 16. The crude protein yields harvested on May 16 were 890 kg/ha for Italian ryegrass and 1,103 kg/ha for triticale and were significantly higher than those harvested on May 3 and May 9. The total digestible nutrient yield(TDN) of Italian ryegrass with 5,223 kg/ha harvested on May 16 was significantly higher than that harvested on May 3 and May 9. The total digestible nutrient yield of triticale with 8,277 kg/ha harvested on June 7 was significantly higher than that harvested during May, but not different from that harvested after June 7. Considering the dry matter yield, crude protein yield and total digestible nutrient yield, it is suggested that the optimal harvesting times for Italian ryegrass and triticale seem to be May 16 and June 7, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.6
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• pp.536-542
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• 1984

Fish eggs and larvae in the western waters of Korea are surveyed during the periods from February to August in 1982. Six species of eggs and forty-two species of larvae are occurred in the survey area. The dominant species occurred during the study periods are Ammodytes personatus, Enedrias sp., Engraulis japonica, Callionymus sp., Gobiidae, etc. Major spawning month and ground of each species are estimated from the data, i.e., occurrence month and abundance of eggs and larvae by survey month and area, as well as the optimum water temperature and salinity for spawning.