• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.2
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• pp.31-44
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• 2016

This study analyzed pore water pressure, earth pressure and settlement through field monitoring on the project site in which raising embankments are being built through backside extension, and compared the behaviors of seepage analysis, slope stability analysis and stress-strain during flood water levels and rapid drawdown under steady state and transient condition. The variation of pore water pressure showed an increase during the later period in both upstream and downstream slope, with downstream slope more largely increased than upstream slope overall. The variation of earth pressure increased according to the increase of embankment heights, while the change largely showed in the upstream slope, it was slowly increased in the downstream slope. The settlements largely increased until 23 m as embankment heights increased, and showed very little settlement overall. Under a steady state and transient conditions, the seepage quantity per day and leakage quantity per 100 m of embankment against total storage were shown to be stable for piping. The hydraulic gradient at the core before and after raising embankments was greater than the limit hydraulic gradient, showing instability for piping. The safety factor of upstream and downstream slopes were shown to be very large at a steady state, while the upstream slopes greatly decreased at a transit conditions, downstream slopes did not show any significant changes. The horizontal settlements, the maximum shear strain and stress are especially distributed at the connecting portion of the existing reservoir and the new extension of backside. Accordingly, the backside extension method should be designed and reinforced differently from the cases of other types reservoirs.

• Research in Plant Disease
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• v.21 no.2
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• pp.89-93
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• 2015

This study was carried out to develop the economic thresholds for the control of bacterial spot of red pepper. The correlation between diseased leaf rate and yield in field was Y=-0.724X+281.58, $R^2=0.78$, $r=-0.88^{**}$. The correlation between diseased leaf rate and yield loss in field was Y=0.813X+15.95, $R^2=0.78$, $r=0.88^*$.We found that control thresholds was below 30.3% diseased leaves rate per plant in field. The economic control thresholds for bacterial spot of red pepper was below 16.3%.

• Journal of Bio-Environment Control
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• v.25 no.3
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• pp.200-205
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• 2016

This study was conducted in order to investigate the effects that the difference of planting time by a method of cultivation in the non-heated greenhouse and the open field with spring planting had on growth and yield. With regard to the tested variety of Momordica charantia, variety 'Dragon' (Japan Yae 農藝) was selected. And 3 treatments on March 20, April 5 and April 20 for the greenhouse cultivation and 3 treatments on April 20, May 5 and May 20 for the open-field cultivation 1 month later than those for the greenhouse cultivation were planted by the randomized complete block design, and 4 secondary vines were trained. In the results of examining 15-day average atmospheric temperature after planting according to the methods of greenhouse and open-field cultivation and planting time, it was shown that there was a tendency for atmospheric temperature inside the greenhouse to decrease as the planting time was moved up. In particular, the average atmospheric temperature was $16.7^{\circ}C$ when seedling was planted on April 20 in the open-field cultivation, which was approximately equal to $17.0^{\circ}C$ of the average atmospheric temperature when a seedling was planted on March 20 in the greenhouse cultivation. With regard to the date of first harvest by the method of cultivation, it was shown that there was a tendency for the date of first harvest to be earlier in the greenhouse cultivation than in the open-field cultivation, and the date of first harvest was moved up as a seedling was planted earlier for the planting period. The number and weight of harvested fruits per plant showed a tendency which was almost similar to that of total number of harvest days and number of harvests. Thus, the number of fruits was 189 and the weight of fruits was 31,649g in case of the greenhouse cultivation and planting on March 20, which were maximum. In case of planting on the latest planting date : May 20 in the open-field cultivation, the number of fruits was 77 and the weight of fruits was 12,502g, which were at a level of 40% of those of planting on March 20 in the greenhouse cultivation 2 months earlier. The total yield per 10a was 10,228kg in the greenhouse cultivation and was 2.2 times as heavy as 4,607kg in the open-field cultivation with regard to the method of cultivation. For the planting period in the greenhouse cultivation, it was 10,539kg and 10,517kg in planting on March 20 and April 5, which was higher by 9% than 9,629kg in planting on April 20. And in the open-field cultivation, it was 4,785kg in planting on April 20 and 4,872kg in planting on May 5, which was higher by 15~17% than 4,163kg in planting on May 20. Taking the above results into account, it is considered proper to plant Momordica charantia from March 20 to April 5 for the greenhouse cultivation and from April 20 to May 5 or thereabouts when a risk of late frost is gone for the open-field cultivation in southern area.

• Journal of the Korean Statistical Society
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• v.36 no.4
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• pp.479-488
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• 2007

The elliptic random field is an extension to the Gaussian random field. We proved a theorem which characterizes the elliptic random field. We proposed a heuristic approach to derive an approximation to the distribution of the size of one connected component of its excursion set above a high threshold. We used this approximation to approximate the distribution of the largest cluster size. We used simulation to compare the approximation with the exact distribution.

• Communications of the Korean Mathematical Society
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• v.7 no.1
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• pp.33-36
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• 1992

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.5
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• pp.308-312
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• 2013

The monitoring of chemical dynamic changes in controlled horticultural lands is very important for agricultural sustainability. Field monitoring was performed to evaluate the soil chemical properties of 200 controlled horticultural soil samples in Gyeongnam province every 4 years from 2000 to 2012. Soil chemical properties such as pH, amount of organic matter, available phosphate, nitrate nitrogen, and exchangeable potassium, calcium, magnesium, and sodium were analyzed. The amount of exchangeable calcium and soil pH were significantly higher in 2012 than in 2000. In 2012, the frequency distribution for values of pH, organic matter, available phosphate, and exchangeable potassium, calcium, and magnesium that were within the optimum range was 16.0%, 22.5%, 11.5%, 3.5%, 2.5%, and 5.0%, respectively. Especially, available phosphate and exchangeable calcium were excess level with portions of 76.0% and 96.5%, respectively. These results indicated that a balanced management of soil chemical properties can reduce the amount of fertilizer applied for sustainable agriculture in controlled horticultural lands.

• Journal of Agricultural Extension & Community Development
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• v.8 no.1
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• pp.41-58
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• 2001

The purpose of this study was to develop plans for activating the 4-H clubs in Korea. Data for this study were collected from 125 members in 4-H clubs and 140 extension educators who participated in 4-H activity. Total of 265 responses were analyzed after data screening. The Statistical Package for Social Sciences(SPSS) for Windows for the personal computer were used to analyze the data. Frequency, percentage, ANOVA, and LSD test for post-hoc interpretation were employed to analyze the data with a statistical significance level of .05. Based on the conclusions of this study, following recommendations were offered: To activate rural youth organizations, especially 4-H clubs in Korea the following measures should be included in the plans for activation; 1) To classify membership into student and non-student clubs to focus on the needs of active members; 2) To establish clear objectives for club activities; 3) To enhance field-oriented operation of clubs; 4) To develop various activity programs that members could be fascinated; 5) To promote subject matter specialists in order to support club activities effectively; and 6) To clarify functions and roles of extension service centers and non-governmental organizations in order to support club activites.

• Korean journal of applied entomology
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• v.60 no.2
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• pp.201-202
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• 2021

We confirmed the convenient bioassay method for the black cutworm, Agrotis ipsilon in semi-field conditions. And we surveyed the susceptibility to commercial pesticides of A. ipsilon, which feeds Chinese cabbage through this bioassay process. As a result of the test, six soil mixing insecticides and eight soil drenching insecticides showed more than 90% insecticidal activity.

• Research in Plant Disease
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• v.13 no.3
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• pp.152-156
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• 2007

Incidences of leaf blight of lily cultivars Raizan and Casa Blanca in the open field cultivation were 50% and 45.4%, respectively, while those in the green house cultivation were significantly reduced to 1.5% and 1.9%, respectively, In the green house, the incidences of the disease in sprinkler watering cultivation were $14.5{\sim}16.5%$, while those in drip watering cultivation were only $1.5{\sim}2%$. Incidence of the disease was severe in the field where the lily was cultivated successively for 2 to 3 years. Isolation frequencies of B. elliptica from overwintered plant debrises such as leaves, stems, capsules, and bulbs were 43.3%, 46.7%, 60% and 0%, respectively, while those of B. cinerea were 10.3%, 0%, 3.3% and 0%, respectively, Incidence of leaf blight in the field where diseased plant debris was cleaned was 7.3%, while that in the field where diseased plant debris was not cleaned was 56.5%. Incidences of the disease in the field where coverages of soil surface with black vinyl, bark or rice straw were used were 6.6%, 8.2% and 11.3%, respectively, while that in the field where the coverage was not used was 21.3%.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.1
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• pp.164-172
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• 1997

Two parameter technique that uses far-field stress and displacement distributions was applied to composite laminates in order to calculate mode II energy release rate, $G_{II}$ . The $G_{II}$ calculated by two parameter technique was compared with that calculated from the crack closure method to inspect the effectiveness of two parameter technique. Sensitivity study of two parameter technique to the crack extension size was also performed. The results showed that both methods produced comparable $G_{II}$ results. In particular, it was found that although the crack closure method was affected by the crack extension size, the two parameter technique was less affected by the crack extension size.