• Research in Plant Disease
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• v.19 no.3
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• pp.196-200
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• 2013

This study was carried out to investigate yield loss due to soybean leaf spot disease caused by Cercospora sojina Hara and to determine the economic threshold level. The investigations revealed highly significant correlations between disease severity (diseased leaf area) and yield components (pod number per plant, total grain number per plant, total grain weight per plant, percent of ripened grain, weight of hundred seed, and yield). The correlation coefficients between leaf spot severity and each component were -0.90, -0.90, -0.92, -0.99, -0.90 and -0.94, respectively. The yield was inversely proportional to the diseased leaf area increased. The regression equation, yield prediction model, between disease severity (x) and yield (y) was obtained as y = -3.7213x + 354.99 ($R^2$ = 0.9047). Based on the yield prediction model, economic injury level and economic threshold level could be set as 3.3% and 2.6% of diseased leaf area of soybean.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.6
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• pp.418-421
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• 2002

This study was carried out to clarify the effect of sowing method in four planting densities on growth and root yield of Cynanchum wilfordii. vine diameter, number of branches, number of branched roots, and root length, were greater in seedling transplanting than in direct sowing. In planting densities, main vine length, number of branches, and number of tillers were increased at higher planting density, but vine diameter, leaf length, leaf width, root length, and root diameter were increased at lower planting density. fresh root yield was greater in seedling transplanting than in direct sowing. In seedling transplanting, it was 53% higher in 27 plants per unit area than 1,680 kg/10a in 17 plants per unit area. Therefore, seedling transplanting in 27 plants per unit area showed most effective for increasing root yield of Cynanchum wilfordii.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.2
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• pp.78-83
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• 2001

Two rice cultivars of the japonica type, ozone-resistant Ilpumbyeo (IL) and ozone-susceptible Keu-mobyeo#l (KM) were exposed to ozone ($O_3$) at 0.15 ppm for 30 days. The available nutrient regimes were varied by doubling the supply of nitrogen (N), phosphorus (P) and potassium (K) within a basic fertilizer status (N, P, K; 15, 12, 12 kg l0$a^{-1}$). There was little difference on plant height between ozone-treated and nontreated plants. The most significant ozone stress on tiller number was shown on the 30th day of ozone exposure. Slight recovery from ozone stress was noted on the 60th day. On the 30th day, tiller number was greatly decreased by 40.8% in IL and 64.6% in KM, whereas at a high nitrogen supply regime (2N), it was decreased by 21.4% in IL and 42.7% in KM as compared to the control not treated with ozone at basic fertilizer status. The inhibition of tiller production caused by ozone exposure was alleviated on the 60th day. In both cultivars, number of spikelets per plant and weight of 100 grains were affected little by the ozone treatment irrespective of nutrient regime. However, the number of panicles per plant and yield were reduced significantly. In both cultivars, yield of ozone-treated plants with 2N status was 12.4-16.1 % higher than that of the ozone-treated plants with basic nutrient status. A significant yield decrease of 47.8% and 33.4% was observed for IL and KM, respectively, in ozone-treated plants with higher potassium (2K) status.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.1
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• pp.34-44
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• 1996

Several major agronomic traits of 4 isogenic lines for tillering(Kindred, Morex)were investigated under the different seeding rates and seedling mortality grown in the pots. The normal-tillering phenotypes had higher grain yield(46％) and leaf area index(56％) than their uniculm isogenic counterparts. The assortment rate(69％) and 1,000 grain weight(27％) in uniculm type were greater than the normal type. Uniculm plants were earlier in heading(4∼8days) and maturing(2∼3 days) dates compared with their counterparts. The grain yield was fitted to linear regression, ranged 0.659g to 0.5g per spike number. On increasing the seedling mortality rates, the grains per spike and 1,000 grain weight were slightly decreased, but the grain yield per plot was decreased markedly because of decrease of spikes per plot. The assortment rate, leaf photosynthetic capacity and reproductive tiller number were increased with increase of seedling mortality. The grain yield was largely dependent on the number of spikes per plot on occurrence of seedling mortality. For the uniculm genotypes to be introduced and bred into a present leading variety, the isogenic lines were precisely tested in the open field for a couple of years.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.2
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• pp.143-148
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• 1999

Soil moisture condition is an important limiting factor in growth and yield in rice culture. The purpose of this study was to compare the influence on the growth, yield and Quality of rice subjected to soil moisture stress (SMS) at different growth stages. Ajaponica rice cultivar, Dongjinbyeo, was cultured under flooded conditions in a plastic container filled with silty loam soil. The container was subjected to SMS until the initial wilting point (IWP) coincided with about 10% in soil moisture content and about-200 kPa in soil matric potential, and was then irrigated again, at 6 and 5 of main growth stage in 1996 and 1997, respectively. At maturity, the plant height, tiller number, leaf area and top dry weight were decreased more in SMS treatments at the early stage than the late stage. The averaged yield index of SMS to control in both years was lowest at meiosis (62.5%), which primarily resulted from lower percent ripened grain and 1,000 grain weight, and second＇ reduced the spikelet number per panicle and panicle number per hill, and followed at tillering stage (68.5%) which resulted from the lower production in tiller number and top dry matter during and after SMS treatment. The percent-age of read rice in SMS plants varied with the treatment stage as order of lower at meiosis (44.0%), heading (53.9%), panicle initiation (70.1%), tillering (72.1%), ripening (75.8%) and 5 days after transplanting (DAT) (79.0%). Protein content in brown rice was slightly larger in SMS at late growth stage than the control, while the contents of fat and ash differed very little between SMS and control. Contents of Mg and K and Mg/K in brown rice with SMS were lower at some treatment stages such as at ripening or panicle initiation.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.82-96
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• 2019

A semi-submersible structure has been widely used for offshore drilling and production of oil and gas. The small water plane area makes the structure very sensitive to weight increase in terms of payload and stability. Therefore, it is necessary to lighten the substructure from the early design stage. This study aims at an optimization of hull structure based on a sophisticated yield and buckling strength in accordance with classification rules. An in-house strength assessment system is developed to automate the procedure such as a generation of buckling panels, a collection of required panel information, automatic buckling and yield check and so on. The developed system enables an automatic yield and buckling strength check of all panels composing the hull structure at each iteration of the optimization. Design variables are plate thickness and stiffener section profiles. In order to overcome the difficulty of large number of design variables and the computational burden of FE analysis, various methods are proposed. The steepest descent method is selected as the optimization algorithm for an efficient search. For a reduction of the number of design variables and a direct application to practical design, the stiffener section variable is determined by selecting one from a pre-defined standard library. Plate thickness is also discretized at 0.5t interval. The number of FE analysis is reduced by using equations to analytically estimating the stress changes in gradient calculation and line search steps. As an endeavor to robust optimization, the number of design variables to be simultaneously optimized is divided by grouping the scantling variables by the plane. A sequential optimization is performed group by group. As a verification example, a central column of a semi-submersible structure is optimized and compared with a conventional optimization of all design variables at once.

• Journal of Ginseng Research
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• v.22 no.4
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• pp.299-303
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• 1998

To know possibility of raw ginseng production for white- and red-ginseng by direct-sowing culture, seeds were directly sowed or seedlings were transplanted at soil condition of sandy loam in ginseng field. After cultivation, the characters of 5-year-old ginseng were investigated. Number of survived plants was increased with increase the seeding quantity in direct-sowing culture, the survived plants in direct-sowing culture was higher than that of transplanting one. Rate of the numbers of survived plants to numbers of seeds sowed in plots of 134 or 90 seeds sowed per tan, 180 x 90cm area, inspire of high number of survived plant was high compared to that of transplanting culture. Occurrence rate of rusty root of ginseng in direct-sowing culture was low significantly compared to that of transplanting culture. Root yield showed in the order of 134, 268, 90 seeds sowed, the values of yield in direct-sowing culture were high obviously compared to that of transplanting one. Individual root weight was increased with decrease the seeding quantity, however, the root weight in plot of 90 seeds sowed showed almost equal the weight in transplanting culture. The number of usable raw ginseng for white- and red-ginseng was increased with decrease of the seeding quantity; the numbers were higher than that of transplanting culture remarkably. We concluded that optimum seedling rate in direct-sowing culture of ginseng was 90 to 134 seeds per tan considering the yield per area and production rate of large root.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.3
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• pp.153-157
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• 2001

To evaluate the effect of liquid pig manure application, the growth and yield of rice and the quality of infiltration water were investigated with application of different amounts of liquid manure. At this study, liquid pig manure was treated with 100, 200, 300 and 400% of recommending nitrogen fertilizer level, respectively. Liquid manure with application rate more than 200% of recommending N fertilizer level (11kg) caused to increase of plant height and number of tiller at panicle formation stage, but it caused the plant disease and pest and plant lodging. In those treatment, number of panicles per hill and number of spikelets per panicle were increased, but yield of rice was less than chemical fertilizer treatment due to low rate of ripeness and 1,000 grain weight. $NO_3-N$ concentration in infiltration water sample collected at 90 cm of soil depth was increased with increasing application amount of liquid manure. With liquid manure application more than 200% of recommending N fertilizer level, it affected negatively on yield and environment such as groundwater quality.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.3
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• pp.147-152
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• 2001

This study was carried out to investigate the effect of application time and amount of liquid pig manure on growth and yield of rice plant and infiltration water quality. Liquid manure treatment with higher application rate and closer application time to transplanting time showed higher plant height and number of tiller at panicle formation stage, but it caused the plant disease and pest and lodging. In liquid manure treatment with higher application rate, number of panicles per hill and number of spikelets per panicle were higher but yield of rice was less than chemical fertilizer treatment due to low rate of ripeness and 1,000 grain weight. $NO_3-N$ concentration in infiltration water sample was increased with increasing application amount of liquid manure and closer application time to transplanting of rice plant. With consideration yield of rice and environment such as groundwater quality, the proper application amount were 150% and 100% of recommending N fertilizer level (11kg) at before winter and April or May treatment, respectively.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.5 s.113
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• pp.41-49
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• 2005

This paper deals the effect of anthraquinone (AQ) on the contribution of sulphidity in kraft pulping of sapwood. The pulping conditions namely- active alkali concentration, pulpingtime, temperature and liquor ratio were varied in low ($15\%$) and high ($30\%$) sulphidity. $0.1\%$ AQ was added in the low and high sulphidity pulping with varying active alkali concentration and cooking time. At optimum conditions, low sulphidity kraft process produced about $44\%$ pulp yield with kappa number of about 23. But in high sulphidity kraft process kappa number was reduced to about 20 at the same yield. An addition of AQ reduced alkali requirement by $2\%$ on oven dried raw material and cooking time by 1 hour to produce pulp yield of about $44\%$ at kappa number 20. AQ is more effective in low sulphidity pulping than the high sulphidity pulping. The breaking length of kraft-AQ pulp was slightly higher than that of kraft pulp.