• Journal of Korea Water Resources Association
• /
• v.53 no.11
• /
• pp.999-1013
• /
• 2020

Weather modification research has been actively performed worldwide, but a technology that can more quantitatively prove the research effects are needed. In this study, the seeding effect, the efficiency of precipitation enhancement in weather modification experiment, was verified using the radar data. Also, the effects of seeding material on hydrometeor change was analyzed. For this, radar data, weather conditions, and numerical simulation data for diffusion were applied. First, a method to analyze the seeding effect in three steps was proposed: before seeding, during seeding, and after seeding. The proposed method was applied to three cases of weather modification experiments conducted in Gangwon-do and the West Sea regions. As a result, when there is no natural precipitation, the radar reflectivity detected in the area where precipitation change is expected was determined as the seeding effect. When natural precipitation occurs, the seeding effect was determined by excluding the effect of natural precipitation from the maximum reflectivity detected. For the application results, it was found that the precipitation intensity increased by 0.1 mm/h through the seeding effect. In addition, it was confirmed that ice crystals, supercooled water droplets, and mixed-phase precipitation were distributed in the seeding cloud. The results of these weather modification research can be used to secure water resources as well as for future study of cloud physics.

• Journal of Gastric Cancer
• /
• v.1 no.3
• /
• pp.136-143
• /
• 2001

Purpose: The prognosis for gastric cancer with peritoneal seeding is very poor, and the role of surgical intervention is limited. We evaluated the effect of radical removal of primary and metastatic lesions on survival in gastric cancer with peritoneal seeding. Materials and Methods: From May 1989 to March 1999 at Kosin University Gospel Hospital, 115 patients revealed gastric cancer with peritoneal seeding but without liver or lung metastasis and without follow-up loss. The study group included 86 patients who underwent surgery for radical removal of primary gastric and metastatic peritoneal lesions. The control group included 29 patients who experienced incomplete removal of primary or metastatic lesions. Both groups received intraoperative intraperitoneal chemotherapy using mytomycin or cisplatin, and 25 patients underwent postoperative intravenous chemotherapy. Results: The median survival times in the study and the control groups were 13 months and 4 months, respectively (p<0.0001). The 1-year, 2-year, and 5-year survival rates were, respectively, $50.6\%,\;18.1\%$, and $11.3\%$ in the study group and $14.8\%,\;3.7\%$ and $0\%$ in the control group (p<0.0001). In the study group, neither postoperative intravenous chemotherapy nor microscopic invasion of the resection margin had any effect on survival, but intraoperative intraperitoneal chemotherapy and degree of peri-toneal seeding, especially the amount of peritoneal seeding, had an effect on survival. In the control group, neither intraperitoneal nor intravenous chemotherapy had any effect on survival, but resection of the primary gastric lesion improved survival. Conclusion: Radical removal of primary gastric and metastatic peritoneal lesions improved the survival rate for gastric cancer with peritoneal seeding. However, a randomized prospective study is needed to correctly evaluate the effect of intraperitoneal or intravenous chemotherapy.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.14 no.2
• /
• pp.125-131
• /
• 1994

This experiment was canied out to study -the effects of different seeding date on the yields and nutritional value of Pearl millet. Seeding dates were $S_1$,$S_2$,$S_3$,$S_4$, and $S_5$, and harvest dates were $S_1$, (7 July) and $S_2$, (18Augst), respectively. The results were summarized as follows: 1. Plant length was not influenced by seeding date at each harvest. The seeding date at $S_4$,showed the longest plant length of 90.4 an on average per year, which was longer by 17 cm compared to 73.3 cm harvested at $S_5$. 2. Total dry matter yield was not significantly different among seeding dates. Total dry matter yield in 1993 increased according to delayed seeding date from $S_1$ to $S_4$. Dry matter yield of 17.3 tonha was obtained in $S_4$. 3. The relative yield of leaf tended to increase with delayed seeding date, and varied from 60% to 69%. 4. Dry matter ratio decreased with delayed seeding date from $S_1$,(20 April) to $S_5$ (30 May), and varied from 15.6% to 12.3%. 5. Crude protein content of leaf at 1st and 2nd harvest and stem at 1st harvest were significantly different among various seeding dates. Avenge crude protein content increased with delayed seeding date from 9.0% at $S_1$ (20April) to 12.8% at (30 May) $S_5$ (30 May). 6. NDF and ADF of leaf at the 1st harvested were significantly different among seeding dates. NDF content decreased with delayed seeding date from 61.9% to 57.8%, and ADF content decreased with delayed seeding date from 34.8% to 32.2%.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.25 no.1
• /
• pp.17-22
• /
• 2005

This experiment was conducted to investigate the effect of seeding dates and rates on the productivity and nutritive value of hairy vetch(Vicia villosa Roth) at experimental field of Grassland and Forage Crops Division, National Livestock Research Institute, RDA, Suwon from 1999 to 2000. The experimental design was consisted of split-plot design with three replications. The main plot was seeding dates(25 Aug., 15 Sep. and 5 Oct.) and the subplot was seeding rates(20, 30 and 40 kg/ha). Late seeding dates increased the plant height and delayed the flowering stage as 1 or 2 days. The dry matter(DM) content was decreased with low seeding rates, and the trend was same in the all plots. Average crude protein(CP) content was $24.1\%$ and increased with delayed seeding date and lower seeding rate. The content of acid detergent fiber(ADF) and neutral detergent fiber(NDF) was increased with higher seeding rate, but seeding date did not affect. In vitro dry matter digestibility(IVDMD) of hairy vetch tended to decrease with high seeding rate, and total digestible nutrient(TND) did not show significant difference among seeding rates. Average relative feed value(RFV) of hairy vetch showed 140 which means very high quality. Dry matter and CP yield was decreased with delayed seeding date. The results of this experiments indicated that seeding in middle-August with 40 kg/ha would be recommended to produce the highest yield and quality f3r the cultivation of hairy vetch in middle part of Korea

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.46 no.1
• /
• pp.47-52
• /
• 2001

In order to develop more stable seedling stand method in wet direct rice seeding culture, the effect of making the drainage ditches was studied in both methods of broadcast seeding on floody paddy surface and puddled-soil drill seeding. In a broadcast seeding on floody paddy surface, the ditching after seeding using a tractor or small ditch maker improved the seedling stand, and reduced the floating seedling and herbicide injury by accelerating the drainage. Suitable ditching time was at 2 days after seeding (DAS) for the tractor and at 3 DAS for the ditch maker. In the puddled-soil drill rice seeding culture, the ditching before seeding with a ditch maker at 3 days after draining effectively improved the seedling stand due to quick draining through well formed the seeding furrows. In the puddled-soil drill seeding, seedling stand number showed higher in both ditching plots synchronized with seeding compared with both only draining treatment at 1 DAS without ditching and the flooding plot condition for 6 DAS. And the suitable ditching depth was 6 cm, as considered the ditching status and drained status. These results suggest that the ditching in wet direct rice seeding is an resonable practice for improving the seedling stand through the accelerating drainage of field.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.44 no.3
• /
• pp.236-242
• /
• 1999

To examine the seedling stand and growth as affected by early seeding dates of dry direct seeded rice in the Honam plain area of Korea, Dongjinbyeo was seeded at six seeding dates from early March to late April in rice fields of silty loam soil(Jeonbuk series) at the National Honam Agricultural Experiment Station (NHAES) for two years, 1996 and 1998. Seedling stand decreased slightly. with an early seeding date, but it produced more than the optimum seedling number except for the seeding of 25 March in 1996. Days to emergence was significantly longer, as seeding date was earlier, and days to emergence by early seeding was shortened only by 8 days because the mean air temperature was lower in 1996 than average, while in 1998, the reduction effect was nine to twenty five days because the mean air temperature was higher than average. In early seeding, various weeds occurred at the emergence date of rice and dominant weeds were Alopecurus aequailis, Ludwigia prostata and Rorippa islandica. NH$_4$$^{+}$ -N content in the soil at the 5th leaf stage and maximum tillering stage were lower, as the seeding date was earlier when nitrogen was split applied as basal and top dressed in 1996, while it was not significantly different among seeding dates when nitrogen was intensively applied as a top dressing in 1998. Tiller number at the maximum tillering stage and panicle number/m$^2$ were more, as seeding date was earlier in 1996, while it was not different in 1998. Filled grain rate and 1,000 grain weight was not different among the seeding dates. Milled rice yield was significantly decreased in the seeding before the middle of March, but in the seeding after late March, it was not varied when compared with the normal seeding date in 1996, while in 1998, there was no difference among seeding dates. From the above results, in consideration of seedling stand, weed occurance, rice growth and milled rice yield, the critical optimum early seeding time in the southern plain area may lie in early April. But it was suggested that when soil moisture is proper for seeding practices, seeding amount is increased and nitrogen is applied after plumule emergence of rice, milled rice yield may not be reduced in the seeding of middle or late March, compared with the seeding in April.l.

• Korean Journal of Plant Resources
• /
• v.25 no.6
• /
• pp.700-706
• /
• 2012

Influences of different seeding dates on growth, seed yield, fatty acid composition and oil content were investigated in flax plants for two years. The results indicated that plant height in early seeding date was higher than that of delayed seeding dates during first season. Furthermore, seeding date also significantly affected the ripened seed rate and the rate increased with the delay in seeding date in first season. Seed yield in the first crop season was significantly higher than the second crop season. Palmitic acid showed variation in different seeding dates. Contrarily, stearic acid was stable and did not changed by different seeding dates. Linolenic acid was found in highest amount in all seeding dates consecutively in two cropping years. Highest oil content was recovered from the seeds of flax sown at 29 Apr. and May 9 in first and second cropping year respectively.

• Current Research on Agriculture and Life Sciences
• /
• v.18
• /
• pp.33-42
• /
• 2000

A field case study was performed to investigate the effect of shallow ponding in paddy field on irrigation water requirement of direct seeded rice. In addition, an economic analysis was made to see the effect of no-till direct seeded rice on cost reduction. A field study was performed at a 2.1ha paddy field in Kimjae city, Chonbuk province from 1991 to 1999. Various direct seeding methods such as dryland seeding, wetland seeding, and no-till wetland seeding were introduced. Then, cost reductions due to the direct seeding and no-till were calculated. In addition, to investigate the effect of shallow ponding on irrigation water requirement, field measurements such as irrigation water volume, drainage water volume, rainfall depth, and ponding depth, were made at a 40a plot within the same area in 1988 and 1990. The results of the shallow ponding study showed that the irrigation water depth, rainfall, and the drainage depth were 379mm, 458mm, and 448mm in 1988 growing season, and 274mm, 819mm, and 736mm in 1990, respectively. The shallow ponding irrigation method saved irrigation water by about 20% with higher yield compared with the traditional method. The economic analysis showed that won \640,000 per ha can be saved by direct seeding due to no nursery cost, and \1,220,000 per ha due to no-till and no nursery cost. The yields ranged 540 to 640 kg per 10a during the study period with an average of 590kg per 10a. If these cropping techniques with no-till direct seeding and shallow ponding depth for rice cropping prove to be advantageous with further study, they can be adopted for the most of the paddy fields in Korea.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.12 no.1
• /
• pp.67-70
• /
• 1992

The experiment was conducted to evaluate the effect of the different seeding date on the dry matter yield and chemical composition of oat for forage. The crops wrc sccdcd on August 3l(lirst). Scptember IO(second). and September 20(third seeding date) and were taken on November 24, 1991. The results are summarized as follows : 1. The plant heights were 68, 54 and 40 cm at first, second, and third seeding date, respetively. 2. Dry matter (DM) content decreased with delaying seeding date from first to third seeding date. DM varied from 18.6 to 14.9 %. 3. Leaf weight ratio increased with delaying seeding date from first to third seeding date, varied from 51 to 67 %, but stems decreased from 49 to 33 %. 4. The dry matter yields per ha decreased with delaying seeding date: it was 5.670. 3.960 and 2.310kg at first, second and third seeding date. Significant differences has been obtained among date(P<. 05). 5. The content of crude protein increased with delaying seeding date from first to third seeding date. varied from 16.3 to 22.6%. but NDF and ADF content decreased.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.43 no.4
• /
• pp.264-268
• /
• 1998

The experiment was conducted to clarify irrigation requirement and percolation rate in rice paddy. The four rice cultural system of no-tin, till, transplanting, and direct seeding condition were treated in the lysimeter filled with sandy loam soil. The amounts of irrigation and soil percolation were measured daily, and irrigation requirement was estimated. The daily percolation was 19.5 l/$\textrm{m}^2$ in no-till direct seeding on flooded paddy surface, 17.4 l/$\textrm{m}^2$ in both of till-direct seeding on flooded surface and no-till transplanting, and 15.2 l/$\textrm{m}^2$ in transplanting plot. This is equivalent to 19.5, 17.4, and 15.2 mm per day, respectively. Highest irrigation requirement was 3,770 l/$\textrm{m}^2$ in no-till direct seeding plots. Others were 3,249, 2,577, and 2,321 l/$\textrm{m}^2$ in till-direct seeding, no-till transplanting and transplanting plot, respectively. The estimated irrigation requirement of no-till transplanting, till-direct seeding and no-till direct seeding was increased by 11, 37, and 59% compared to till-transplanting plot. Percolation rate of no-till transplanting, till direct seeding and no-till direct seeding was increased by 12%, 40%, and 66%, respectively compared to the till-transplanting plot. The percolation rate in paddy soil was increased greatly after reproductive stage of rice.