• Proceedings of the Korean Society of Crop Science Conference
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• 2006.04a
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• pp.478-479
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• 2006

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1846-1851
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• 2003

Approximate optimization has become popular in engineering field such as MDO and Crash analysis which is time consuming. To accomplish efficient approximate optimization, accuracy of approximate model is very important. As surrogate model, Kriging have been widely used approximating highly nonlinear system . Because Kriging employs interpolation method, it is adequate for deterministic computer simulation. Because there are no random errors and measurement errors in deterministic computer simulation, instead of classical DOE ,space filling experiment design which fills uniformly design space should be applied. In this work, various space filling designs such as maximin distance design, maximum entropy design are reviewed. And new design improving maximum entropy design is suggested and compared.

• Korean Journal of Plant Resources
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• v.19 no.6
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• pp.697-699
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• 2006

To find out the best complex fertilizer for high yielding of rapeseed crop, experiment was conducted on complex fertilizers at the experiment field in upland of rapeseed in Mokpo Experiment Station, Nat'l Institute of Corp Science, RDA, Korea. Experiment was laid out in randomized complete block (RCBD) design. The effects of complex fertilizer (22-22-11) on the number of branches, pod length, percentage of seed set and seed yield were highest but on the plant height, ear length, and number of pods per ear were negligible. On th basis of the results reported above, for getting higher yield of rapeseed crop, among the tested fertilizers complex fertilizer (22-22-11) gave the superior performance and is recommended for application.

• Korean Journal of Medicinal Crop Science
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• v.2 no.1
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• pp.26-31
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• 1994

This experiment was conducted to study the effect of growth characteristics and yield by different planting density on Ligusticum chuanxiong Hort.Number of stem, leaf and branch on main stem were plant reduced by increasing the plant density. Stem height was showed the highest at $50{\times}15cm$ planting density, but diameter did not show significant difference at different planting density. Stem number in $m^2$ of field area showed negative correlation with leaf number and branch number on main stem. The height of first branched node became longer by increasing stem number, leaf number and branch number on stem in $m^2$ of field area. Rhizome yield showed negative correlation with stem number and leaf number per plant, but showed positive with stem number in $m^2$ of field area leaf number and branch number of main stem. Root and rhizome weight per plant decreased by increasing planting density, but root and rhizome yield in $m^2$ of field area were increased by high planting density.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.1
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• pp.23-30
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• 1988

This experiment was carried out to obtain the basic information for the improving of leaf quality by topping time and depth in flue-cured tobacco. Development of palisade parenchyma and spongy parenchyma were in order of button stage＆gt;early flower stage＆gt;late flower stage by topping time, and were in order of 4th leaf topping from floral axis＆gt;2nd leaf topping from floral axis＆gt;floral axis by topping depth. When 2nd leaf from floral axis were topped at late flower stage in A grade field and at early flower stage in B grade field, total sugar to nicotine ratio ralating to organoleptic characteristics were desirable as 9.0 and 9.7, and petroleum ether extract contents relating flavor of flue-cured tobacco were high as 9.9% and 8.4%, respectively. In ecological tissue, percentage of direct effect on quality were 43.2% in palisade parenchyma. 26.5% in spongy parechyma. 17.7% in tissue ratio, 6.7% in leaf thickness, 3.1% in intercellular space, 2.8% in leaf type and in chemical components, were 40.6% in nicotine. 35.7% in T-sugar/nicotine, 10.0% in total sugar, 7.0% in T-nitrogen/nicotine, 4.6% in total nitrogen, 2.1% in petroleum ether extract. The optimum topping depth were desirable at topping under second leaf from floral axis at late flower stage in A grade field and at early flower stage in B grade field for good leaf quality.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.2
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• pp.78-84
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• 2016

This paper is focused on the measurement and analysis of an atmospheric electric field which is caused by thunderclouds. The electric field due to thunderclouds changes very slowly. For this reason, the extremely low frequency E-field sensor needs to be used for measuring the atmospheric electric field strength. The balloon-carried E-field sensor system with the time constant of 1sec was designed and fabricated. The electric field sensor consists of $100mm{\times}100mm$ copper plate, active integrator, high pass and low pass filters and batteries. The measurements of atmospheric electric fields were made by the balloon-carried E-field sensor and radiosonde, which sends the data back to ground in real time. From the calibration experiments, the response sensitivity of the E-field sensor was 0.154mV/kV/m in the frequency range of less than 1kHz. As a result from the actual experiment of the atmospheric electric field, the electric field signals were observed from the altitude of about 2.5km. Also, as the altitude was increased, the detected electric field wave oscillated with the fluctuation of sensing plate. The proposed method seems suitable for measurements of atmospheric electric fields, because it is inexpensive, simple to use and launch.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1994.04a
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• pp.375-384
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• 1994

Depending upon the eye and head movement, the visual field is often classified into three categories; stationary field, eye field and head field. To investigate the effect of background condition on the size of stationary field, an experiment was conducted, in which the subject was instructed to search a target with distinct orientations. In each trial, a single target was presented on the rear-view screen projected by the two-field tachistoscope, with the visual angle subtended 4.3.deg. vertically and horizontally. Density, meridian and subject showed a significant effect on stationary field at .alpha.=0.01, where density was inversely proportional to the size of stationary field. The size of the stationary field on horizontal axis was larger than that on vertical axis, and that on right and below meridian also larger than on left and lower meridian. The shape was found to be horizontally oriented oval and statistically asymmetric with respect to horizontal and vertical axes. The regression equation to predict stationary field on the given background condition was suggested. These results were expected to be used as a designing guideline when arranging displays and controls on panels such as automobile display panels, cockpits, etc. In addition, it can be inferred from the results that eye field and head field are also subjected to the influence of background condition.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.1
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• pp.43-57
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• 2002

This paper introduces an analysis method to predicting the flow characteristic of flow field around otter board In order to develope a high performance model. In this experiment, it is used a numerical analysis of flow field through CFD(Computational Fluid Dynamic), PIV method in which quantitative, qualitative evaluation is possible. In this experiment, it is used PIV method with flow filed image around otter board in order to analysis of flow characteristic. The result compared flow pattern with analysis result through CFD and also measurement result of lift and drag force coefficient carried out in CWC(Circulating Water Channel). The numerical analysis result is matched well with experiment result of PIV in the research and it is able to verify In the physical aspect. The result is as follows ; (1) It was carried out visibility experiment using laser light sheet, and picture analysis through PIV method in order to analysis fluid field of otter-board. As a result, the tendency of qualitative fluid movement only through the fluid particle's flow could be known. (2) Since PIV analysis result is quantitative, this can be seen in velocity vector distributions, instantaneous streamline contour, and average vorticity distributions through various post processing method. As a result, the change of flow field could be confirmed. (3) At angle of attack 24$^{\circ}$ where It Is shown maximum spreading force coefficient, the analysis result of CFD and PIV had very similar flow pattern. In both case, at the otter-board post edge a little boundary layer separation was seen, but, generally they had a good flow (4) As the result of post processing with velocity vector distributions, instantaneous streamline contour and average vorticity distributions by PIV, boundary layer separation phenomenon started to happen from angle of attack 24$^{\circ}$, and from over angle of attack 28$^{\circ}$, it happen at leading edge side with the width enlarged.

• Research in Plant Disease
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• v.24 no.1
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• pp.26-32
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• 2018

Fusarium wilt on strawberry plants caused by Fusarium oxysporum f. sp. fragariae (Fof) is a major disease in Korea. The prevalence of this disease is increasing, especially in hydroponic cultivation in strawberry field. This study assessed the effect of nutrition solution pH and electrical conductivity (EC) on Fusarium wilt in vitro and in field trials. pH levels of 5.0, 5.5, 6.0, 6.5, 7.0, and 7.5 were assayed in vitro and in field trials. EC levels at 0, 0.5, 0.8, 1.0, and $1.5dS{\cdot}m^{-1}$ were assayed in field trials. Mycelial growth of Fof increased with increasing pH and was highest at $25^{\circ}C$ pH 7 and lowest at $20^{\circ}C$, pH 5.0 in vitro. The incidence of Fusarium wilt was lowest in the pH 6.5 treatment and highest in the pH 5 treatment in field trials. At higher pH levels, the EC decreased in the drain solution and the potassium content of strawberry leaves increased. In the EC assay, the severity of Fusarium wilt and nitrogen content of leaves increased as the EC increased. These results indicate that Fusarium wilt is related to pH and EC in hydroponic culture of strawberry plants.

• Korean Journal of Weed Science
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• v.1 no.1
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• pp.21-29
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• 1981

Nationwide survey of weed population in paddy rice field was conducted from 1760 fields all around Republic of Korea in 1981. The weed species observed include 2 species of grasses, 7 species of sedges, and 18 species of broadleaf weeds, and the dominant weed species were Monochoria vaginalis, Sagitraria trifolia, Potamogeton distinstus, Sagittaria pygmea and Cyperus serotinus. More and many weeds were growing in single cropped field than double cropped field. In single cropped fields, weed population was reduced when autumn plowing was conducted. In double cropped fields, more weeds were growing in barley or wheat grown fields than vegetable gown fields. Among the five paddy soil types, more weeds were growing in saline soils and poorly drained soils than others. The proportion of annual and perennial weeds in national average was 44% and 56%, and perennials became more dominant in central part of the peninsula. Autumn plowing and double cropping appeared to reduce the perennial weed population, however, the increased perennial weed population, presumably due to continuous use of herbicides which controls mostly annuals, seemed to an urgent problem to be solved.