• Journal of the Korean Geographical Society
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• v.47 no.3
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• pp.347-358
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• 2012

This study aimed to investigate the change of wind speed during winter and summer seasons for 50 years(1961-2010). It were analyzed the mean wind speed, maximum wind speed, windy days and storm days on January and August of 13 weather stations in South Korea. The mean wind speed was decreased in the coastal region(Busan, Jeju, Ulsan, Pohang) in winter and summer seasons. Also it was similar to windy day. The relationship between wind speed and mean temperature has negative correlation in winter season. The relationship is low in summer season. The number of windy day and storm day has negative relation with monthly mean temperature.

• Journal of Aquaculture
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• v.16 no.4
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• pp.245-251
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• 2003

Sexual maturation and gametogenic cycle of the hard shelled mussel, Mytilus coruscus were investigated by means of histological method. Specimens were collected monthly in Hansan Bay of south coast, Korea from January to December 2002. Sex of the clam was dioecious. The gonads are composed of a number of gametogenic follicles. The gonad index (GI) was reached the maximum in February (3.40), and the minimum in August (1.18). The monthly variation of condition index (CI) coincides with gonad index. The main spawning occurs between February and March. The gametogenic cycle of the clam could be divided into six stages: resting (August to November), multiplicative (November to December), growing (December to January), maturation (January to February), partially spent (February to April) and completely spent/degenerative stage (April to July). Sex ratio (♀/♂) was 1:0.96.

• 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.

• Korean Journal of Plant Resources
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• v.21 no.1
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• pp.47-51
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• 2008

This study was carried out to get the basic data for safflower cultivation according to sowing date by growth analysis for 2 years form 2003 to 2004 at Institute of natural product in Uiseong, G.B.A.R.E.S.. Safflower(Cheongsoo cultivar) was seeded at March 1st, April 1st, May 1st, and July 1st in field. The necessary date for germination was 24 days, when safflower was seeded at March 1st, but it was 8 days which sowed at April 1st and when the seed was sowed at high temperature period, the necessary date for germination was getting short. The necessary date for flowering was the same trend as germination; it took 104 days at March 1st, 79 days at April 1st, 65 days at May 1st, and 58 days at July 1st sowing treatment. The safflower growth was the most vigor when it was sowed at March 1st. T/R(Top/Root) ratio was gently increased during growing season, but when the seed was sowed at July 1 st, it was low compare to sowing at March 1st and April 1st. RGR(Relative growth rate) was the highest during shoot growth stage, but it was rapidly decreased after flowering. CGR(Crop growth rate) was increased at branching stage, and the increasing velocity was slightly decreased just before flowering, and it was increased again at flowering and at this stage, CGR was the highest, and then it did not increased. NAR(Net assimilation rate) was the highest at shoot growth stage during growing season, and was the highest which was sowed at March 1st.

• Journal of the Korean Society of International Agriculture
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• v.30 no.4
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• pp.370-375
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• 2018

In order to promote the mechanized cultivation of perilla for seed, which has been increasing in cultivation area and production recently as demand increases according to the health-functional effects, we carried out this experiment to determine the optimum sowing time of perilla to minimize the seed loss at harvest and increase the yield. We used two different types of perilla varieties, 'Sodam(small-branch)' and 'Deulsaem(multi-branch)', and the sowing time was June 15, June 30, July 15 and August 1. As the sowing time is late, days of growth from sowing to flowering were shortened, and they were shortened from 14, 26 and 31~32 days on June 30, July 15 and August 1 as compared with June 15, respectively. And, the stem length and culm diameter were shortened or tapered and the number of nodes tended to decrease. The number of effective branch was 82%, 61% and 56% on June 30, July 15 and August 1 as compared with June 15, respectively. Accordingly, it seems to make against in securing the yield from July 15. And, the lowest cluster height was generally shorter as the sowing time is late, and the height was below 15cm on July 15 and August 1. It seems that this may work against the machine harvest. There was a high degree of significance between the sowing time and the yield. Although, the total yield was not statistically significant among June 15, June 30 and July 15, the ratio of shattering seed at harvest was in order of July 15, August 1(30.3%)> June 15(15.3%)> June 30(13.5%). Therefore, the net yield except for shattered seed was higher in order of June 30${\geq}$ June 15> July 15> August 1. This tendency was characteristic regardless of variety and sowing method. And, the protein content in perilla seed increased as the sowing time was delayed, and the content was the highest on August 1. The content of crude fat was relatively high on June 15 and July 15 in 'Sodam', and June 30 and July 15 in 'Deulsaem', respectively. And, the content of linolenic acid was found to be the highest on August 1. As a result, the optimal sowing time for machine harvest of perilla for seed is about June 30. At this time, it is determined that the sowing time is the most suitable to be advantageous in increasing the yield of perilla seed, while minimizing the seed loss due to the shattering at harvest.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.6
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• pp.400-404
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• 2000

Hairy vetch (vicia villosa Roth), leguminous green manure crop, can increase soil fertility and reduce chemical nitrogen application for cash crop such as spring corn. More yield of hairy vetch is needed at planting cash crop to obtain higher effect of green manure. Hairy vetch waa seeded on Sep.10, Oct.1, and Oct. 20 and at 10, 20, 30 and 40 kg/ha of seeding rate respectively, in 1996 and 1997, Dry matter and nitrogen yield of hairy vetch were measured on May 1 in 1997 and 1998. Proper seeding rate of hairy vetch was 30 kg/ha irrespective of years and seeding dates. Above-ground dry matters of hairy vetch on May 1 in 1997 and 1998 decreased according to delayed seeding, and those were 5.5-7, 4-4.5, 1.3-2.2 ton/ha on Sep. 10, Oct. 1 and Oct 20 of seeding date, respectively in seeding rate 30-40 kg/ha. Also nitrogen yield of hairy vetch on May 1 decreased according to delayed seeding, and those were 220-280, 160-180, 60-100kg/ha on Sep. 10, Oct. 1 and Oct 20 of seeding date, respectively in seeding rate 30-40kg/ha. Therefore, we suggest that hairy vetch has to be seeded earlier in autumn to obtain high green manure yield in spring. To determine the detailed optimum seeding time in autumn, hairy vetch was seeded on Aug. 20, Aug. 31, Sep. 10, Sep. 20, and Sep. 30 in 1999 and was harvested on April 22, April 27, and May 2 in 2000, respectively. Dry matter and nitrogen yield of hairy vetch by seeding in late August were higher than those by seeding in September indicating that dry matter of hairy vetch were 7-8, 6-7, 4-5, 2-3 ton/ha and nitrogen yield were 240-290, 200-260, 150-220, 70-120 kg/ha, respectively when seeded on Aug. 20, Aug. 31, Sep. 10, Sep. 20 and Sep. 30 and harvested on April 22-May 2. Increase of dry matter and N yield of hairy vetch by 10days delayed harvest was higher in late August seeding than in September seeding. So hairy vetch should be seeded in late August if possible to obtain much more green manure yield and be seeded until September because green manure yield decrease rapidly when seeded after October.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.3
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• pp.95-101
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• 1980

Optical properties were studied at the fishing ground of anchovy in the southern part of Korea based on seven oceanographic stations from May to August and November to December, 1977. Submarine daylight intensity was measured at intervals of 1m depth in the upper 30 m layer by the underwater luxmeter (Toshiba # 9). The absorption coefficient of the sea water ranged from 0.066 to 0.619 (mean 0.21) for six months. The transparency ranged from 2.6 to 16 meters (mean 8.4m). The relationship between absorption coefficient (n) and transparency (D) was k=1.70/D. The mean water color in this area was 4.8 $(3\~10)$ in Forel scales. The rates of light penetration for daylight at four different depths were computed with reference to the surface light intensity. The mean rates of light penetration were $69.38\%(25.43\~88.10\%),\;30.35\%\;(4.38\~59.46\%),\;12.53\%\;(0.75\~33.51\%),\;5.7\%(0.18\~20.27\%)$ at depths of 1, 5, 10 and 15 m respectively.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1600-1604
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• 2010

본 연구에서는 도시화나 지리지형적 특성에 따른 강수량의 분포와 추세를 분석하였다. 이를 위하여 서울을 포함하여 전국 56개 기후관측지점에서 1973년부터 2006년까지의 강수량 자료를 수집하여 분석을 실시하였다. 분석을 위하여 계절적 영향을 고려하여 1월, 4월, 7월 그리고 10월의 월평균 일별과 연평균 일별 강수량 추세를 분석하였다. 그리고 이들 연구지역에 대해서 GIS 분석을 이용하여 지리지형적 특성을 파악하였고, 도시화 정도를 파악하기 위하여 토지피복자료를 분석하였다. 연구결과 연평균 일별 강수량 추세는 대부분의 연구지역에서 증가하고 있으며, 4월과 10월의 강수량은 감소추세에 있고, 1월과 7월의 경우 증가추세에 있는 것으로 나타났다. 도시화 영향을 고려할 때, 강수량 변화는 연별이나 7월의 경우 증가추세를 보이나 1, 4, 10월 강수량의 경우 감소추세를 보였다. 또한 도시화율이나 해안 근접성과 비교하여 연구지역의 평균고도는 연평균 및 월평균 강수량 추세에 가장 중요한 영향을 미치고 있음을 알 수 있었다.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.3
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• pp.185-189
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• 2000

The object of this study was to determine the optimum seeding dates of "Donganbyeo", "Daesanbyeo", Hoanbyeo", "Nonghobyeo", and "Gwnganbyeo" for direct seeding on dry paddy in Youngnam region. Dry seeds of these varieties were sown 5 times with 10-day intervals from April 20 to May 30. It took 13 to 14 days from sowing to emergence. It was shortened in the delayed seeding date, but the emerged seedlings per unit area was decreased as the seeding date was advanced before May. Heading date was delayed as seeding was delayed. Culm length, panicle length and number of spikelets per panicle was not affected by seeding date, but number of panicle per $m^2$ and ripened grain ratio were high from April 30 to May 10 seeding date. Consequently, the optimum seeding date for high yield of "Donganbyeo", "Daesanbyeo", "Hoanbyeo", "Nonghobyeo", and "Gwanganbyeo" was estimated May 3, May 2, May 10, May 8, and May 1, respectively and "Gwanganbyeo" was estimated May 3, May 2, May 10, May 8, and May 1, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.4
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• pp.234-241
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• 1975

Reproductive cycle of Haliotis discus hannai Ino was studied based on the samples which were collected in Yeosu area from January, 1973 to December, 1974. Particular emphasis was paid on the seasonal variation of gonad maturity factor, coefficieot of gonad maturity, fatnesss, and relationship of gonad weight to growth of the abalone. seasonal fluctuation of water temperature and induction of artificial spawnings were also checked. The abalone of this area spawns twice a year: spring spawning(early May-late July) and Autumn spawning(early September-late November). peak spawning occurs from late May to middle of June for spring spawning: it occurs from late September to early November for Autumn spawning. Gonad maturity factor was closely related to the spawning seasons. For the spring spawning Gonad maturity factor reached to its maximum value as 18.84 in April; for the Autumn spawning it reached to its maximum value as 22.65 in September. Annual minimum value was 12.65 in January. Annual maximum values of coefficient of gonad maturity were 44.10 in May and 49.05 in September and the annual minimum was 10.09 in January. Fatnesswas highest in July as 0.221 and it was lowest in October as 0.1058. Ratios of shell length to gonad weight were formulated as follows : $$In\;September\;GW=0.000003710SL^{3.7860}$$ $$In\;January\;GW=0.000021198SL^{2.8564}$$ $$Annual\;mean\;GW=0.00000005013SL^{4.2273}$$ Relations of total weight to gonad weight were formulated as follows : In September GW=0.1918TW-4.9231 In January GW=0.0992TW-0.1759 Annual maan GW=0.1568UW-3.5256.