• Korean journal of applied entomology
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• v.45 no.3 s.144
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• pp.275-282
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• 2006

Insect pests attacking the leaf of lettuce (Lactuca sativa) were surveyed in environmentally frendly leaf-lettuce-greenhouses in Hwaseong, Namyangju, and Suwon from 2003 to 2004. Sixteen insect species of eleven families in eight orders were collected in greenhouses. Among them, Acyrthosiphon solani, Frankliniella occidentalis, and Autographa nigrisigna were the most serious pest species because of their damage ratio was over 30%. Population of Acyrthosiphon solani showed the highest peak one or two times between mid-April and early June in both the second and the third cropping period. Frankliniella occidentalis reached the highest peak one or two times, the first peak between mid-June and the late July, and the second peak between the mid-August and the mid-October.Autographa nigrisigna reached the highest peak one or times between early June and late July and in the mid-August to late October. The highest peak occurrence of A. solami was observed in early June as many as 4,836 nymphs and adults per 100 leaves. And for F. occidentalis it was in early July occurring 437 larvae and adults per 100 leaves, for A. nigrisigna in early October occurring 42 larvae per 100 leaves. The density of F. occidentalis and its damage as well was greater in soil culture than in hydroponic culture, but in case of both A. solani and A. nigrisigna no such difference between cropping systems was found.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.4
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• pp.337-348
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• 2017

The tension of warp from trawler and sea-floor contact can generate tilt and wake turbulence around otter boards. Preliminary measurements of otter board tilt and 3-D flow velocity during bottom trawl operations were taken using a vector instrument to investigate the effects of wake turbulence at the trailing edge of the otter board. Tilt data (i.e., yaw, pitch, and roll) at 1 Hz and flow data (velocities in the towing, lateral, and vertical directions) at 16 Hz were analyzed to determine their periods and amplitudes using global wavelet and peak event analyses. The mean period (${\pm}standard$ deviation) of the tilt from the peak event analysis ($5{\pm}2s$) was longer or double than that of flow velocity ($3{\pm}2s$). The two periods also had a significant linear relationship. The turbulence rate of flow was 30-50% at the trailing edge and was closely related to roll deviation. The frequency of phase difference ratios (i.e., peak time differences between tilts and flow periods) was significantly different from random occurrence in two trials, possibly due to side tidal effects. However, in the other trials, flow peaks were random, as shown by the even peak times between tilts and flows. Future studies should focus on reducing tilt variation, wake turbulence, and bottom contact to stabilize otter board motion.

• The korean journal of orthodontics
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• v.7 no.1
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• pp.13-22
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• 1977

The author investigated the timing of land and wrist ossification events taking place in the hamate and pisiform by means of roentgenographic examination and its relation to the peak growth velocities in body height. Materials obtained included 493 sheets of X-ray films taken from 257 boys ana 236 girls aged between 7 and 17 years lived in Seoul area. The results indicate that; 1) The average ages at occurrence of initial ossification of the hook of the hamate were 12 years 3 months in boys and 10 years 1 month in girls. 2) The average ages at which advanced ossification of the hook of the hamate occurred were 13 years 7 months in boys and 11 years 11 months in girls. 3) Initial ossification of the pisiform appeared at 13 years 0 month in boys and 10 years 2 months in girls. 4) All three ossification events in hand and wrist, and peak growth velocity in body height occurred earlier in girls than in boys. 5) Initial ossification in the hook of the hamate and pisiform preceded or coincided with peak growth in body height in most boys and girls, on the other hand, advanced ossification in the hook of the hamate occurred around peak growth in body height but in girls did it after peak growth in body height. 6) It would appear that initial ossification in the hook of the hamate or in the pisiform, both for boys and girls, provides a better indication of approaching peak adolescent growth in body height. 7) Advanced ossification in the hook of the tamale would indicate that the period of cercumpuberal peak growth had teen entered or finished.

• Korean journal of applied entomology
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• v.43 no.2
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• pp.103-109
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• 2004

Seasonal occurrence of Japanese gall-forming thrips, Ponticulothrips diospyrosi Haga et Okajima, and its damage pattern on leaves and fruits were studied at sweet persimmon orchards in Gimhae (orchard A, B) and Changwon, Gyeongnam. Korea in 2002 and 2003. Monitoring adults by yellow sticky traps and inspecting each developmental stage in damaged rolled-leaves revealed that the overwintered adults moved to sweet persimmon orchard from late April to late May, and oviposited inside the rolled leaves. Adults developed from the eggs showed peak occurrence of the first generation adults in early to mid June. Inspection of rolled leaves indicated that the peak occurrences of eggs, nymphs, and pupae of the first generation took place in early to mid May, late May to early June, and early June, respectively. Each developmental stage showed the second small peaks in the late season. Results suggest that most thrips live a single generation per year, but a small portion may develop to the second generation in persimmon orchards. The percent of damaged leaves was highest in Changwon orchard at 9.7％ in early June. Percentage of damaged fruits increased from 0.84％ in early June to 30.2％ in early September in Gimhae B orchard. It was found that the closer the persimmon trees were to the edge of the orchard, the worse damaged the leaves were. Appropriate timing for incorporation of control measures were discussed in relation to the seasonal occurrence of adults.

• Korean journal of applied entomology
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• v.45 no.1 s.142
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• pp.9-13
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• 2006

Seasonal occurrence of thrips and its damage on fruits were studied at in open field red pepper in Jeonbuk Province. The kind of thrips were Franklinella occidentalis and F. intonsa. The ratio of F. occidentalis was about 30% in periods of survey. Density of thrips increased in late May and showed peak occurrence in early to middle July. The peak occurrence of thrips was appeared at 4 pentad June, 2 pentad July, 3 pentad August, and 4 pentad September. The part of fruit damaged by thrips became discolored and roughed. When turned red, the colors of damaged parts changed from dark brown to yellowish brown. As a result, damage fruits by thrips decreased marketability. The percent of damaged fruits was highest in Imsil at 20.8% in early August. Density of thrips on flowers was highest in middle July.

• Korean journal of applied entomology
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• v.34 no.2
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• pp.147-153
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• 1995

The occurrence of Oriental Tobacco Budworm (OTB), Helicoverpa assulta (Guenee), larvae in early and late planted tobacco fields showed tow or three distinct peaks. The parasitoid, Campoletis chlorideae Uchida, occurred for a short period with one peak following th second peak of OTB in early planted fields. However, in late planted fields, the parasitoid occurred as long as the OTB larvae were abundant. The OTB larval density was higher in late planted fields than in early planted fields. Among four varieties of tobacco, the OBT larval occurrence was relatively high on NC-744 throughout the season. However, more parasitoid cocoons were found in Burleyf-21 and NC-82. The seasonal occurrence of the larval parasitoid, C. chlorideae, assessed by an OTB larval release and recovery method, continued from late June to early September and relatively higher abundance was noticed from early July to late August. In a field cage evaluation of C. chlorideae as a biological control agent of OTB larvae, higher rate of C. chlorideae release (4 females/2$\m^2$) resulted in higher larval parasitism (86.1%) and less leaf damage (8.7%) in tobacco. The leaf damage by OTB larvae was significantly high in the untreatment plot (23.2%) and the lowest damage (1.6%) was recorded in the chemical treatment plot.

• Journal of Korea Water Resources Association
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• v.45 no.12
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• pp.1213-1226
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• 2012

Evolutionary algorithms, which are frequently used in an automatic calibration of watershed runoff simulation models, are unconstrained optimization algorithms. An additional method is required to impose constraints on those algorithms. The purpose of the study is to modify the SCE-UA (shuffled complex evolution-University of Arizona) to impose constraints by a penalty function and to improve performance of the automatic calibration module of the SWMM (storm water management model) linked with the SCE-UA. As indicators related to peak flow are important in watershed runoff event simulation, error of peak flow and error of peak flow occurrence time are selected to set up constraints. The automatic calibration module including the constraints was applied to the Milyang Dam Basin and the Guro 1 Pumping Station Basin. The automatic calibration results were compared with the results calibrated by an automatic calibration without the constraints. Error of peak flow and error of peak flow occurrence time were greatly improved and the original objective function value is not highly violated in the automatic calibration including the constraints. The automatic calibration model with constraints was also verified, and the results was excellent. In conclusion, the performance of the automatic calibration module for watershed runoff event simulation was improved by application of the penalty function to impose constraints.

• The Korean Journal of Ecology
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• v.19 no.1
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• pp.31-37
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• 1996

The chigger mites known as the vectors of Tsutsugamushi disease seriously increased due to the expansion of their habitats by the change of farmland into idle land, arboreta and golf courses with the progress of industrialization. These mites were surveyed for their nymphs in soil of four areas located in the northern part of Kyonggido known as the outbreak areas of Tsutsugamushi disease. Total number of the chigger mites collected in the soil of four surveyed areas was 2576, and two genera and ten species including Leptotrombidium palpale were indentified. Among them L. pallidum was the dominant species with the highest occurrence rate of 62 percent. Nine species occurred on the bank of Changrungchon that has been idled for more than ten years, but six or seven species occurred in Wonhundong and Ilsandong that hans been idled for less than five years. The number of individuals collected was also higher in Changrungchon than the other sites. Seasonal occurrence of these mites showed a peak with 166 mites in November on the west slope and another with 192 mites in February on the east slope of the bank of Changrungchon, but none in June. Component ratio of individual numbers for L. palpale, L. pallidum, L. orientalis and L.scutelaris were 19, 62, 9 and 3 percent, respectively. Individual number of L. pallidum and L. scutelaris appeared to some extent of 397 and 23 mites, respetively.

• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.5
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• pp.64-73
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• 1996

When typhoon occurs, the meteorological conditions get worse and can cause a large damage from storm and flood . This damage, however, can be minimized if a precise analysis of the runoff characteristics by typhoon tracks is used in the flood contorl This paper aims at the analysis of storm occurrence and runoff characteristics by typhoon tracks in Nakdong river basin. Therefore, the data of 14 typhoons which invaded Nakdong river basin during the period from 1975 to 1991 were collected, analyzed, and studied. The major results of this study are as followings; 1) The frequency of the typhoon occurrence here in Korea was affected by the storms three times a year on the average. The highest-recorded frequency was during the months of July to September. 2) The survey of the track characteristics depending on the forms of the storm in the Nakdong river basin showed that typhoon storm advanced from the south of the basin to the north, while the frontal type storm was most likely to advanced from the west to the north. 3) Typhoon tracks are classified into three categories, 6 predictors with high correlation coefficient are finally selected, and stepwise multiple regression method are used to establish typhoon strom forecasting models. 4) The riview on the directions of progress of the storm made it clear that the storm moving downstream from upstream of the basin could develop into peak discharge for ca short time and lead to more flood damage than in any other direction.

• Journal of Korea Water Resources Association
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• v.50 no.1
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• pp.65-73
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• 2017

This study analyzed the peak drought severity and drought duration of the Cheongmicheon watershed from 1985 to 2015 to assess the lag time of peak drought severity between several drought indices. Standardized Precipitation Index (SPI) based on precipitation and Standardized Precipitation Evapotranspiration Index (SPEI) based on precipitation and evapotranspiration were applied as meteorological drought indices. Streamflow Drought Index (SDI) based on runoff data was applied as hydrological drought index. In case of SDI, we used Soil and Water Assessment Tool (SWAT) model for simulation of daily runoff data. As a result, the time of peak drought severity of SDI occurred after the occurrence of SPI and SPEI. The lag time for the peak drought severity, on average, between SDI and SPI was 0.59 months while SDI and SPEI was 0.79 months. As compared with SDI, the maximum delay was 2 months for both SPI and SPEI. This study results also shows that even though the rainfall events were able to cope with meteorological droughts, they were not always available to solve the hydrological droughts in the same time.