• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.836-840
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• 2007

Large-Scale Particle Image Velocimetry (LSPIV)는 Particle Image Velocimetry (PIV)를 자연하천이나 실험실에서 넓은 영역($4m^2{\sim}45,000m^2$)에 적용할 수 있도록 확장시킨 것으로 지난 10여년 이상 세계적으로 널리 이에 대한 연구가 진행되고 있다. PIV는 seeding, illumination, recording 그리고 image processing으로 구성된다. LSPIV(Large Scale PIV)는 PIV의 기본원리를 근거로 하여 기존의 PIV에 비하여 실험실 내에서의 수리모형실험이나 일반 하천에서의 유속측정과 같은 큰 규모의 흐름해석을 할 수 있도록 seeding, illumination에 대한 조정이 필요하고, 촬영된 image에 대한 왜곡을 없애는 작업이 필요하다. LSPIV는 PIV의 네가지 단계를 포함하여 seeding, illumination, recording, image transformation, image processing 및 post-processing의 여섯 단계로 구성되어진다 (Li, 2002). LSPIV를 일반 하천에 적용시, 자연발생적인 tracers - 난류로 인한 표면 교란, 부유물, 수공구조물로 인해서 발생하는 자연 발생되는 거품 - 가 풍부해서 seeding이 불필요한 경우를 제외하고는 정확한 유속장의 해석을 위하여 인공적인 seeding을 필요로 한다. 일반적으로 Seeding 재료로 많이 이용되는 것은 wood mulch, Ecofoam, grain-straw 등이다. 하천에서 자연발생적 혹은 인위적 seeding을 하였을 때 이들 tracers의 물리적인 속성으로 바람에 쉽게 영향을 받고 이로 인하여 실제의 물표면유속을 대표하지 못하는 경우가 있다. 이에 실험실의 개수로에서 여러 가지 이용 가능한 tracers에 대하여 바람에 의한 오차 발생의 정도를 조사하였다. 실험에 사용된 seeding 재료로는 black polypropylene, Ecofoam, white polystyrene의 세가지를 이용하였다. black polypropylene (SG=0.92)과 white polystyrene (SG=0.0125)은 폭 1 m 이내의 개수로 실험 장치에서 유속장의 해석에 많이 이용되고 Ecofoam (SG=0.0065)은 수리 모형실험에서 많이 이용된다. seeding 물질에 따른 바람의 영향을 분석하기 위해서 폭 60cm의 개수로에서 seeding 물질을 변경하면서 펌프의 조작에 의해 3가지 단면평균유속을 발생시키고, 각 평균유속조건에 대해 4가지의 바람세기 - 바람이 없을 때와 팬의 바람세기를 1단, 2단, 3단으로 조정 - 를 발생시켰으며, 개수로위에서 촬영한 이미지의 상류측기준점으로부터 0.3556m 하류 지점을 횡단하는 단면의 표면유속을 측정하여 비교하였고, 그 단면의 중앙에서 물표면 바로 위 지점의 풍속을 측정하였다. 각 Seeding 물질에 대해 팬을 켜지 않았을 때, 즉 바람의 영향이 없을 때 측정한 표면유속을 바람의 세기가 변한 경우의 기준 표면유속으로 이용하였다. 본 연구의 결과 비중이 0.01 내외인 Ecofoam과 white polystyrene에 비해 비중이 0.92인 black polypropylene은 대부분이 물속에 잠겨 있어 흐름과 거의 일치하여 움직임을 알 수 있었다. 또한 흐름의 평균유속이 0.165 m/s의 저유속에서 바람이 tracers에 미치는 영향이 평균유속 0.558m/s인 경우보다 커서, 바람의 세기의 증가에 따라 표면유속 측정값이 급속히 감소되었다. 흐름의 평균유속이 큰 경우에는 바람이 tracer에 마치는 영향이 현격히 줄어듬을 보이고 있다. 결론적으로 유속이 증가함에 따라 바람의 영향은 감소하나, 바람의 영향을 최소화시키기 위해서는 가급적 비중이 큰 물질(0.5

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.spc1
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• pp.47-51
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• 2006

This study was conducted to establish the optimum seeding rate in different soil salinity level for yield stability of broadcasting on flooded paddy surface to the reclaimed saline land of south-western part at Gyehwado substation of the Honam Agricultural Research institute in $2003{\sim}2004$. Soeganbyeo was tested in the Munpo series (fine sand loam) the results obtained is as follows: As seeding rate was higher, the number of seeding stand was increased and the number of seeding stands in the low salinity field is sharply increased than those of the medium salinity field. The length of culm in medium salinity field tends to be shorter than that of the low salinity field and as seeding rate was increased, the lodging is severe. The milled rice yield was increased as up to 9 kg/10a in low and medium salinity soil. Complete rice was no significantly increased over 5 kg/10a seeding rate in low salinity field and over 7 kg/10a seeding rate in medium salinity field. Considering the yield of milled and complete rice, seeding stand and lodging, The proper seeding rate is $5{\sim}7kg/10a$ in low salinity and $7{\sim}9kg/10a$ in medium salinity for broadcasting on flooded paddy surface at the reclaimed saline land of southwestern part.

• Korean Journal of Plant Resources
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• v.18 no.1
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• pp.8-14
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• 2005

This study was carried out to investigate the possibility of double cropping of safflower(Carthamus tinctotious L.) in vinyl house for rainshield culture. Planting methods, i.e., direct seeding as the first crop and direct seeding and transplanting as the second crop, were investigated. Growth characters and establishment were better in the first crop than in the second crop. Between direct seeding and transplanting of the second crop, growth was not significantly different, but establishment was much higher in direct seeding than in transplanting. Seed yield of the second crop was lower $30\~74\%$ than that of the first crop. In planting methods of the second crop, seed yield was higher in direct seeding than in transplanting. Therefore, optimum method of the second crop for double cropping of safflower in the middle parts of Korea was estimated as direct seeding.

• Korean Journal of Medicinal Crop Science
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• v.13 no.6
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• pp.241-244
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• 2005

This study was carried out to compare growth characteristics, and extract and crude saponin contents of 4-year-old ginseng cultured by direct seeding and transplanting cultivation at several farms of the main producing district, Geumsan and Eumsung. Though root weight per plant of direct seeding cultivation was lower than that of transplanting cultivation, but yield of the former was higher than that of the latter owing to high rate of survival plant and Leaf Area Index. Dry matter partitioning ratio of direct seeding cultivation was high in primary root and low in secondary root because direct seeding cultivation elongated the length of primary root, while it suppressed the growth of secondary root. Ratio of rusty root was decreased in condition of direct seeding cultivation, while the contents of extract and crude saponin were lower than that of transplanting cultivation.

• Journal of the Korean earth science society
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• v.36 no.4
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• pp.301-314
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• 2015

The purpose of this study was to investigate the impact of ground-based glaciogenic seeding on orographic clouds in the Daegwallyeong area on 13 March, 2013. The experiments was conducted by releasing silver iodide (AgI) under following conditions: surface temperature below $-4^{\circ}C$, wind direction between 45 and $130^{\circ}$, and wind speed less than $5ms^{-1}$. Two seeding rates, $38gh^{-1}$ (SR1) and $113gh^{-1}$ (SR2), were tested to obtain an appropriate AgI ratio for snowfall enhancement in the Daegwallyeong area. Numerical simulations were carried out by using the WRF (Weather Research and Forecast) model with AgI point-source module which predicted dispersion fields of AgI particles. The results indicated that the target orographic clouds contained adequate amount of supercooled liquid water and that the dispersion of AgI particles tended to move along the prevailing wind direction. To validate the seeding effects, the observation data from FM-120 and MPS as well as PARSIVEL disdrometer were analyzed. In this case study, glaciogenic seeding significantly increased the concentration of small ice particles below 1 mm in diameter. The observation results suggest that SR1 seeding be reasonable to use the ground-based seeding in the Daegwallyeong area.

• Korean Journal of Breeding Science
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• v.43 no.6
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• pp.581-586
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• 2011

'Cheongdam' is a japonica rice variety developed from a cross between SR19200-HB826-34, a line of good germination ability and shoot emergence at low temperature and Juanbyeo, good quality and direct-seeding adaptable cultivar by the rice breeding team of National Institute of Crop Science, RDA in 2006. This variety has 153 days of total growth duration from seeding to maturity in direct-seeding, and 160 days of growth duration from seeding to maturity in transplanting. This is erect plant type with culm length of 74 cm, thick culm, and green leaves. It has large panicle shape with 126 and 140 spikelets per panicle in direct-seeding and transplanting, respectively. Milled rice is transluscent and medium in grain size of non-glutinous endosperm. This variety is susceptible to leaf and neck blast, bacterial blight, stripe virus disease and brown planthopper. The yield potential of 'Cheongdam' is 5.84 MT/ha at ordinary transplanting culture and 5.62 MT/ha and 5.89 MT/ha at wet direct-seeding and dry direct-seeding cultures, respectively in the local adaptability test for three years. 'Cheongdam' would be adaptable to middle and southern plain of Korea for direct-seeding culture and transplanting rice culture.

• Korean Journal of Medicinal Crop Science
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• v.6 no.2
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• pp.160-164
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• 1998

Angelica gigas has been a major medicinal crop in Korea for a long time. This study was to determine optimum seeding time and bolting response by shifting seeding time between November 10, 1993, and August 10, 1994 using promising line, Suwon 2. Days to emergence were similar among seeding times from April 10 to August 10 in Suwon. Seedling duration was shortened 92 days when seeded on July 10 compared with the conventional seeding time of April 10. Productivity of seedling ranging from 0.31 to 0.70cm in diameter was highest of 730 plants per $m^2$ in July 10 seeding. When seeded in July 10, bolting rate was 2.4 percent as compared with 2.6 percent in conventional seeding (April 10). The optimum seeding time was July 10. Seedling quality, survival rate after planting in field, and root yield were greatly influenced by seeding time.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.197-197
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• 2017

In order to reduce the loss of perilla seeds at harvesting stage, different seeding methods and harvesting time had been applied to upland soil in NICS (National Institute of Crop Science), RDA, Milyang, Korea. The seeding methods were divided into hill and drill seeding, and harvesting time were 40%, 60%, 80%, and 100% color-changing of top cluster perilla (cv Deulsaem) seeds. Higher plant height and lowest flower cluster, thinner culm thickness was observed in drill seeding treated plot than hill seeding treated plot. However, field lodging occurred lower at drill seeding treatment (lodging degree 3) than hill seeding plot (lodging degree 5). Harvesting time affected the loss of perilla seeds and the loss rate of perilla seeds were investigated at different color-changing of top flower cluster. When seeds were harvested at 40%, 60%, 80%, and 100% color-changing of top cluster perilla seeds, the loss rate of hill and drill seeding showed no significant differences however the loss rated of 40, 60, 80, and 100 % color-changing of top flower cluster were 1.9% to 3.0%, 3.8% to 3.9%, 8.0% to 10.2%, and 16.1% to 22.7%, respectively. The harvesting time had no significant effects on the yield of perilla seeds. These results suggest that optimum harvesting time of perilla could be recommend at the 60% color-changing of top cluster to reduce the loss of perilla seeds.

• Korean Journal of Weed Science
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• v.7 no.1
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• pp.52-57
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• 1987

To know the effects of weeding periods (weeding from 12 days, 28 days and 42 days after seeding to harvest, and weeding from seeding to 14 days, 28 days and 42 days after seeding) and growing conditions such as transparent polyethylene film mulch (P.E. mulch) and bare soil on growth and yield of peanuts, "Yeongho-Tangkong" was planted on May 10, 1984. Under P.E. mulch, the number of weeds was higher, but the weed dry weight was lower than in bare soil by the middle of July. Sixty days after seedings, the length of main stems in weedy check plots was longer, but shoot dry weight was lower compared to weed free plot. In the correlation coefficients between weed dry weight and the shoot dry weight of peanut on July 14, the growth retardation of peanuts due to weeds was showed earlier under P.E. mulch than in bare soil. Shoot dry weight, shelling ratio, number of seeds per pod, 100 pod weight, and seed yield were higher under P.E, mulch compared to bare soil. But weed dry weight, length of branches, number of pod bearing branches, number of pods per square meters, and pod yield were similar between P.E. mulch and bare soil. Shoot dry weight of peanuts, length of branches, number of pod bearing branches, number of pods per square meters, pod yield, 100 pod weight, 100 seed weight, and seed yield in weed free plots from 28 days after seeding to harvest (28 DAS-Harvest) were higher compared to weed free plots from 42 DAS-Harvest. However, in the weed free plot from seeding to 42 days after seeding seed yield was lower than that of the continuous weeding plot due to lower number of pod bearing branches and number of pods per square meters. When weed was not controlled at the later growth stages of peanuts, reduction in seed yield due to weeds was greater in bare soil than that under P.E. mulch.

• Journal of Korea Water Resources Association
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• v.31 no.5
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• pp.621-635
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• 1998

The feasibility of cloud seeding in Korea is presented from analyses of precipitation, cloud amount, satellite data, and upper air data. The daily mean precipitation over Dae-Kwan-Ryong is the largest(~4.5 mm/day), while the intensity of precipitation (amount of yearly rainfall divided by the frequency of rain days) over Southern area is above 14 mm/day, which shows the largest in Korea. Both the daily mean and the intensity of precipitation over Andong area are the smallest with values of ~2.7 mm/day and ~11 mm/day, respectively. In the meanwhile, the occurrence frequency of appropriate cloud top temperature (-10'~-30') for cloud seeding over the region has a large value (~130 days/year). The precipitation patterns of the region vary with wind direction and intensity calculated from 43 AWSs(Automatic Weather Station) and the additional 7 rain guages which were installed along Northern and Southern part of the Sobaek mountain. The Sc(Stratocumulus) cloud type over Andong is frequently observed, and Cirrus and Altostratus next. From the results, it is estimated that the feasibility of cloud seeding over the area would be high if a proper strategy of cloud seeding is set up. LCL (Lifting Condensation Level) and CCL (Convective Condensation Level) have the most frequency in 1000-950 hPa being occupied 4/9 of total analysis period and in 400-500 hPa, respectively, with both small variations from season to season. The correlation between vapor mixing ratio and CCL is the highest in Summer and the lowest in Winter. It means that the height of cumulus in Summer is high with an abundant water vapor but vice versa in Winter, and that the strategy of cloud seeding should be different with seasons.