• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2009.04a
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• pp.35-39
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• 2009

The equal distribution of the gravity as well as the topographic data is an essential factor in the precision geoid determination. In this study, the area where needs the supplementary gravity survey is assigned through a simulation to build the 5cm level geoid. Based on the current distribution of the gravity data which results in the 8cm level of the precision over all, we extract the area which shows the errors larger than 30 cm. Then, the area is assumed to be filled with gravity data with 2km interval which is turned out to be successfully improving the overall accuracy up to 5cm. Therefore, it is recommended that the supplementary gravity survey should be conducted in mountainous area such as eastern and mid-northern part of Kangwon-Do to achieve the 5cm accuracy on the geoid.

• Journal of the Korean Society for Railway
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• v.12 no.4
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• pp.499-505
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• 2009

This paper evaluated applicability of railroad reference points for determinating geoid heights. For this research, reference points on the Honam express raildroad which contain ellipsoid heights estimated by GPS/Leveling and orthometric heights by leveling were used. Geoid heights were calculated uisng orthometric and ellipsoid heights of 360 railroad reference points, and the RMSE's with respect to different intervals of reference points were analysed which were induced by interpolation methods. The results showed that no significant difference of RMSE's among interpolation. methods. RMSE's of 0-4km interval of reference points were determined within 2cm and 5-8km were within 3cm. Also, this research confirmed that GPS leveling with Geoid model is not auurate enough to be used for railroad surveying as yet.

• The Korean Journal of Pesticide Science
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• v.3 no.2
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• pp.69-73
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• 1999

The insecticidal activities and residues of chlorfenapyr [4-bromo-2-(4-chlorophenyl)-1-ethoxymethyl-5-trifluorornethyl pyrrole-3-carbonitrile] against Thrips palmi was evaluated under laboratory and vinyl house conditions. Effectiveness of chlorfenapyr against T. palmi on red pepper leaves was lasted for 9 days at a concentration of 50 ppm but there was no significant differences between emulsifiable concentration and wettable granule under laboratory conditions. In vinyl house, high toxicity was investigated at 6 hours after application of chlorfenapyr in a concentration of 50 and 100 ppm and insecticidal effect was maintained for 11days after 2 times weekly application in cucumber. Control effect was above 97% against T. palmi larva and larva+adults after 2 times weekly application in vinyl house.

• Journal of Bio-Environment Control
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• v.20 no.4
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• pp.277-282
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• 2011

We carried out shape recognition. We found out cucumber's feature shape by means of neural network and back propagation algorithm. We developed an algorithm which finds object position and shape in real image and we gained following conclusion as a result. It was processed for feature shape extraction of cucumber to detect automatic. The output pattern rates of the miss-detected objects was 0.1~4.2% in the output pattern which was recognized as cucumber. We were gained output pattern according to image resolution $445{\times}363$, $501{\times}391$, $450{\times}271$, $297{\times}421$. It was appeared that no change was detected. When learning pattern was increased to 25, miss-detection ratio was 16.02%, and when learning pattern had 2 pattern, it didn't detect 8 cucumber in 40 images.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.2
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• pp.159-167
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• 2009

To obtain the gravity data with consistent quality and good distribution over Korea, to overcome the difficulties in constructing precision geoid from biased distribution of ground data, to resolve the discrepancy between the ground and ocean gravity data, an airborne gravity survey was conducted from Dec. 2008 to Jan. 2009. The data was measured at the average flying height of 3,000m and the data with cross-over error of 2.21mGal is obtained. The geoid constructed using this airborne gravity data shows the range of 9.34 $\sim$ 33.88m. Comparing the geoid with respect to the GPS/levelling data, a precision of 0.145m is obtained. After fitting, the degree of fit to GPS/levelling data was calculated about 5cm. It was found that there exists large biases in the area of south-western and northern part of the peninsular which is considered to be the effect of distorted vertical datum in Korea. Thus, more investigation on vertical datum would be needed in near future.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.6
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• pp.621-629
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• 2008

Procedures involved in the refinement of the regional geoid for the area encompassing the Korean peninsula and the East Sea are described, and the computational results are provided. A comparison between the geoid height data, the mean sea surface height and the final product of the refinement work is provided and analyzed. The regional marine geoid thus refined seems to have a better resolution, in terms of its correlation with the bathymetry, and shows the bottom features in a more detailed manner when compared with previously used procedures. The general pattern of the computed geoid profile matches reasonably well with the existing studies, where the correlations between the refined regional marine geoid and the bathymetry are (1) 0.44 for the area $117{\sim}142.5^{\circ}E/24{\sim}52^{\circ}N$ and (2) 0.47 for the area $127{\sim}142.5^{\circ}E/32{\sim}50^{\circ}N$ in the East Sea respectively.

• Research in Plant Disease
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• v.30 no.2
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• pp.189-193
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• 2024

Cucumber (Cucumis sativus L.) is substantial economic importance in South Korea, with its cultivation occupying a significant portion of agricultural land. However, sustainable cucumber production requires effective management of various diseases affecting the crop yield. In this study, we explored the potential of Streptomyces sp. S20-465-derived metabolites in controlling cucumber anthracnose disease caused by Colletotrichum orbiculare. This study identified 4-hydroxy-4-methyl-2-pentanone as a potent antifungal compound present in the n-hexane extract of Streptomyces sp. S20-465 culture filtrate. This compound exhibited significant the disease reduction, demonstrating their potential as control agents. Our findings suggest that Streptomyces sp. S20-465-derived metabolite could serve as an effective tool for managing cucumber anthracnose, offering a sustainable approach to enhancing cucumber production. Further research into the application and efficacy of these compounds in agricultural system will be conducted.

• Korean journal of applied entomology
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• v.41 no.3
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• pp.211-216
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• 2002

The present study was aimed to examine the effect of different host plants on the biological property of cotton caterpillar, outbreak pest of cucurbit vegetables. The feeding and oviposition preferences toward cucumber and pumpkin were greater than those toward watermelon, oriental melon, and melon. The periods of egg and larva fed on oriental melon, melon, and pumpkin were longer than those on watermelon and cucumber. The longest pupal period was 10.5 days from cucumber. The hatching rate, pupation rate, emergence rate, and survival rate were observed from different host plants. The hatching rate was the highest on cucumber (87.2%) and the lowest on melon (72.8%). The pupation rate on watermelon and oriental melon (90.0% and 89.1%, respectively) was higher than that on cucumber (62.0%). The emergence rate on cucumber and pumpkin (93.5% and 92.0%, respectively) was higher than that on oriental melon (78.7%). The survival rate from hatching to emergence on watermelon (76.0%) was the highest, and the lowest on cucumber (50.0%). The adult period on melon (21.0 days) was the longest, and the shortest on cucumber (15.5 days) among 5 host plants. Average number of eggs per female on cucumber (281.8 eggs) was the highest, and the least on oriental melon (96.6 eggs). The survivorship on cucumber was the longest (30 days), and the shortest on pumpkin (17 days). The preoviposition period on oriental melon and melon (3.4 days) was longer than that on watermelon (2.1 days) and mean generation time in day (T) on melon was the longest (47.2 days) though they were not significant. The net reproductive rate per generation (R$_{o}$) on cucumber, 191.3, was the highest and the highest intrinsic rate of natural increase (r$_{m}$) was observed from cucumber as 0.127. All these results suggest that the growth ana reproduction of cotton caterpillar varies depending upon the kind of host plants. The analysis of the life table revealed that cucumber and pumpkin were the favorable host plants of cotton caterpillar.

• The Korean Journal of Mycology
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• v.41 no.4
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• pp.261-267
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• 2013

In order to select antagonists for biological control of downy mildew of cucumber, 126 bacteria were isolated from cucumber plants collected from several locations in Korea. Among them, Five isolates were selected as potential biocontrol agents of cucumber downy mildew using a leaf disc bioassay method. In preventive and curative effect tests, the isolate CC110 was found to be effective to control downy mildew on cucumber showing diseased area by 0% whereas that of control was 15.0~18.0%. A bacterium isolate CC110 was identified as Bacillus amyloliquefaciens subsp. plantarum based on phylogenetic analysis using gyrB gene sequence. The culture liquid of isolate CC110 in TSB media were more effective for the control of the disease than those cultured in LB, NB, and KB media in leaf disk bioassay. when undiluted liquid, two-fold, five-fold diluted culture broth, and undiluted liquid, two-fold, five-fold diluted filtrate of isolate CC110 in TSB media were treated, diseased area of cucumber powdery mildew were 0%, 3.0%, 8.0%, 0%, 4.0% and 7.0%, respectively, whereas diseased area in the control was 21.0%. In the cucumber seedling tests, when the culture broth of isolate CC110 in TSB media was treated, diseased area were 35.0%, whereas that of control was 82.0%. When B. amyloliquefaciens CC110 was treated four times at five-day interval in the vinylhouse test, the control effect of cucumber downy mildew was higher than that treated three at seven-day interval.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.1
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• pp.81-89
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• 2011

The previous land gravity data in Korea showed locally biased irregular distribution. Especially, this problem was more serious in the mountainous area where the data density was significantly low. The same problem appeared in GPS/Levelling data thus the precision of the geoid could not be improved. From 2008, new gravity and GPS/Levelling data has been collected by the unified control point and survey on the benchmark project which were funded by the national geographic information institute. The newly obtained data has much better distribution and precision so that it could be used for update precision of geoid model. In this study, the new precision geoid has been calculated based old and new gravity data and this model showed 5.29cm of precision compared to 927 points of GPS/Levelling data. And the degree of fit and precision of hybrid geoid has been calculated 2.99cm and 3.67cm. The new gravimetric geoid has been updated about 27% over whole country. And it showed 42% of precision update due to collection of new gravity data on the Kangwon/Kyeongsang area which showed quite low distribution. In 2010, about 4,000 points of gravity and 300 points of GPS/Levelling data has been obtained by unified control and survey on benchmark project. We expect that new data will contribute to updating geoid precision and veri tying precision more objectively.