• Korean journal of applied entomology
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• v.51 no.4
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• pp.383-388
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• 2012

This study was conducted to assess damage to the welsh onion by Acrolepiopsis sapporensis Mastumura (Lepidoptera: Acrolepiidae) during the summer season, and to estimate the economic injury level (EIL) which results, providing basic data for pest management. The adult peaks of A. sapporensis in Suwon were observed in March, April, May, and September of 2009 and 2010 through the use of pheromone traps. The feeding of A. sapporensis results in white lines on the surface, and holes within welsh onions. During the entire larval period, one larva was able to damage 1.6 leaves and punch 11.9 holes, resulting in a total damaged leaf area of $1,321.6mm^2$. Through cage experiments and larval releases, a reduction of the mean number of leaves, increased percentage of leaf damage, and reduction in gross weight and marketable weight were observed. We could obtain a regression equation that showed a clear positive correlation between pest density and percentage of damaged leaf. Using this equation, the EIL of A. sapporensis on welsh onion was calculated to one larva per 10 plants based on 7% leaf damage observed for welsh onion.

• The Korean Journal of Pesticide Science
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• v.14 no.2
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• pp.133-137
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• 2010

A field investigation was carried out for two years to analyze yield loss due to soybean anthracnose caused by Colletotrichum truncatum and to determine its economic threshold limit. Anthracnose severity in terms of % diseased pods was negatively correlated with yield, number of normal seeds per plant and number of pods per plant, and positively correlated with % abnormal seeds with correlation coefficients of -0.85, -0.78, -0.64, and 0.80, respectively. A simple linear regression model was obtained as Y=-1.7781X+164.22 with $R^2$=0.8092, when the soybean yields (Y) were predicted using anthracnose severity (X) as an independent variable. The yield levels could be predicted as high as 80.92%. Based on this equation, spray threshold without economic considerations was estimated as 6.9 in % pods infected with anthracnose. Economic threshold limit and economic spray threshold able to compensate the costs of fungicide sprays were determined as 11.9% and 9.5%, respectively.

• Korean journal of applied entomology
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• v.46 no.3
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• pp.409-414
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• 2007

Economic injury levels and economic thresholds were estimated for the american serpentine leafminer (Liriomyza trifolii) on greenhouse eggplant. Liriomyza trifolii density was increased until the late June and decreased after the July in innoculation on may 17. Growth of an aerial plants and fruits were not different in treatment respectively. But total number of fruits and yields were decreased on higher inoculation density. Whereas the rate of yield loss was increased. The rates of damaged leaf by L. trifolii were increased on higher inoculation density and the peak was 65%. The number of commodity fruits and the rates of commodity fruit were become lower than non-treatment (72.2%). The rates of damaged leaf area were 5.3, 11.7, 19.7, 25.7% on inoculation densities and the rates of yield loss were 0.6, 4.8, 9.8, 14.7%, respectively. There existed close correlation between rate of yield loss and inoculation density (Y = 0.76779X + 0.298354, $R^2\;=\;0.9599$). Considerated of the results, the economic injury levels of L. trifolii on eggplant greenhouse was 6.1 adults per 4 plant and the economic thresholds was 4.9 adults per 4 plant.

• The Korean Journal of Pesticide Science
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• v.14 no.3
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• pp.241-246
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• 2010

Field experiments were carried out to establish economic threshold for com borer (Ostrinia furnacalis (Guen$\'{e}$e)) on waxy com plants by examining the number of adult insects caught in pheromone traps and the injury levels of waxy com which were artificially controlled. Adult com borers were lured into the pheromone traps during the whole growth period in five areas in Gangwon province including Chuncheon. The number of com borers trapped was the greatest in Chuncheon followed by Cheolwon and Hongcheon, and the same trend was observed for injury level of waxy com. Based on marketable yield data of waxy com plants related to the artificially-controlled injury levels at tassel stage, spray threshold was determined as the injury level of 11~15%, where the injury of com plants exceeded the economically admitting level.

• Korean journal of applied entomology
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• v.50 no.4
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• pp.289-293
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• 2011

This study was conducted to develop economic injury level (EIL) of onion thrips, Thrips tabaci, on welsh onion (Allium fistulosum L. var) in the early transplanting stage. The changes of welsh onion biomass, yield loss, and T. tabaci density were investigated according to the inoculation periods of T. tabaci. In the early transplanting stage of welsh onion, the yield loss (%) increased with increasing inoculation periods: 17.0, 53.3, 38.4, and 80.8% yield loss in 5, 10, 15, and 20 d inoculation periods, respectively. The relationship between Cumulative Insect Days (CID) of T. tabaci and yield loss (%) of welsh onion was well described by a nonlinear logistic equation. Using the estimated equation, EIL of T. tabaci on welsh onion was estimated to 30 CID per plant based on the yield loss 12% (an empirical gain threshold 5% + marketable rate 93% of welsh onion). ET was calculated to 24 CID, which corresponds to 80% of EIL. Until a more defined EIL-model is developed, the present results should be useful for T. tabaci management in early growth stage of welsh onion. The effect of T. tabaci attack on the yield of welsh onion in late growing season (120 days after transplanting) was also examined. The yield of welsh onion increased at a low population density of T. tabaci and decreased at higher densities, showing a typical over-compensatory response.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.646-646
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• 2015

임진강은 북한지역이 유역면적의 60%에 달하고 2000년대 초부터 북한의 4월5일 댐과 황강댐과 남한의 군남과 한탄강 홍수조절지로 인해 물의 흐름과 강의 모습이 급격히 변화하고 있다. 기후변화 측면에서도 한반도 중부지역으로 기온 증가와 계절별 유출량, 특히 봄철의 유출량 감소가 전망되는 지역이다. 임진강 본류 유량 감소는 북한 측의 영향은 자료가 전무하고, 남측에서는 횡산, 군남 등 일부 수위표 자료만이 가용한 수준이다. 현재까지 자료로 보면, 2014년에 연강수량이 예년의 50% 수준이었던 점이 본류 유량 감소의 주 원인이었고, 다른 원인은 군남 홍수조절지의 저류 수준이 그 직하류 유량 변동에 영향을 미치고 있는 것으로 나타났다. 유량감소 영향은 2014년 장단반도 일대 파주지역에서 가장 극심하였고, 유량 감소와 연동된 염도 변동이 가중되면서 모내기철 농업용수 공급이 어려웠다. 유량 감소 피해는 농업보다 어업분야에서 그 체감 정도가 극심하였고 경제적 피해도 심각했다. 체감하는 주민들 대부분은 댐 건설 이후 하도와 수변의 침식과 퇴적 등 하천의 역동성이 변화함을 느끼고 있고, 그로 인해 어업과 수생태계가 지속가능성하지 않을 거라는 우려가 팽배해 지고 있다. 지금까지 파악된 임진강 유량 감소의 수준과 피해 정도가 앞으로 어떻게 변화될지, 그 수준, 심각성, 경제적 피해와 환경적 가치나 서비스 제약 등에 대해 면밀한 검토가 필요하다. 하천의 흐름이 단절, 변경되어 야기되는 직간접적 변화를 인정하고 이를 지속가능하게 보완할 방안이 논의되어야 할 시점이다. 무엇보다 수환경과 수생태계의 변화 정도를 파악하기 위한 장기모니터링이 절실하고 그 결과의 해석을 통해 새로운 대안을 모색해 나가야 할 것이다. 2014년 혹은 그보다 심각한 강우량 감소 재현을 대비하고, 기후변화와 남북한 문제까지를 고려한 임진강 관리가 필요하다. 단기적으로는 농업용수 공급을 위해 하천 본류는 물론 가용한 저수지, 지하수 등 대체 자원을 적극 활용하는 등 비상급수체계를 운영해야 한다. 그러나 기후변화 등 장래 여건이 수량 압박을 가중할 것을 고려, 유역의 용수수급과 변동성에 대한 재평가가 시급하다. 보다 면밀한 평가는 횡산, 군남 등을 포함한 남북유역의 상황을 장기모니터링하고 북한 지역의 기초 자료 확보를 위한 여건을 마련해야 한다. 보다 합리적 분석을 위해 임진강 수계와 유역을 국가하천에서 국제하천으로 격상하는 방안이나, DMZ와 연계한 남북공유 하천으로 관리하는 등의 새로운 대안이 절실하다. 국제수로협약 등을 통해 접경지역의 하천관리를 공동으로 하고 있는 외국 사례의 시사점도 접목해 볼 필요가 있다. 무엇보다 임진강 관리를 좀 더 제도적 틀안에서 확립해 가기 위해 지역정부로서의 경기도, 중앙정부 주체로 국토부와 통일부가 보다 협력적인 관계 정립과 역할 배분을 논의해야 한다.

• Korean journal of applied entomology
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• v.54 no.1
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• pp.1-6
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• 2015

This study was conducted to estimate the economic injury level (EIL) to leaf broccoli (leaf vegetable) by the diamondback moth (Plutella xylostella L.) in 2007 and obtain basic data for pest management. To investigate the relationship between initial density of diamondback moth larvae and broccoli leaf yield, experimental plots with five treatments (0, 0.5, 1.0, 1.5 and 2.0 larvae per plant) as initial density were established. We inoculated larvae on cheesecloth covering to survey changes in larval density. When grown for consumption, leaves of broccoli are harvested in periods. High levels of larvae were associated with significant reductions in leaf yield. There were 0%, 15%, 35%, 42%, 44% yield reductions due to a density of 0, 0.5, 1.0, 1.5, 2.0 diamond back moth larvae per plant, respectively, 25 days after larva inoculation. The regression equation used to predict leaf yield based on the number of initial larvae per plant was y = 1636-394x($R^2=0.79^{***}$>). EIL of the diamondback moth on leaf broccoli was 2~3 larvae per 10 plants for a damage level of 5%. The economic threshold was 1~2 larvae per 10 plants. Thus, diamondback moth management should be initiated when 1~2 larvae appear on 10 plants.

• Journal of the Korean Geographical Society
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• v.33 no.2
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• pp.179-190
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• 1998

한반도에 내습하는 태풍의 발생빈도와 강도는 큰 편은 아니나 우리는 거의 해마다 태풍으로 인한 재해를 경험하고 있다. 특히 태풍에 의한 경제적 손실은 1960년대 이후 경제개발과 도시화로 인한 인구과밀지역에서 크게 나타나고 있다. 본 논문에서는 태풍재해의 대책을 수립하는데 필요한 기초자료를 마련하기 위한 방향을 제시하고자, 태풍재해를 유발하는 기상적 요인과 더불어 경제.사회적 조건이 재해의 규모 및 강도에 미치는 기여도가 상당히 크다는 것을 밝히고자 하였다. 한반도에 큰 피해를 남기는 태풍의 진로는 서해를 따라 북진하다가 반도부를 거쳐 동쪽으로 빠져나가는 E경로로서 한반도의 동쪽을 통과하는 진로를 취할 때 보다 더 큰 영향을 끼친다. 재해지역의 공간분포는 대체로 남해안 지역에 집중되어 있다. 태풍재해는 일반적으로 태풍중심에서부터 피해지역가지의 최단거리, 강수량, 최대풍속 등의 기상적 요긴과 피해지역의 토지이용 및 그 지역의 산업구조를 포함하는 사회.경제적 요인 그리고 재해대책수준 및 태풍예보기술 등 다양한 원인에 의해 태풍의 피해의 정도가 결정됨을 태풍재해의 공간분포와 발생요인의 분석결과 알 수 있었다. 침수로 인한 피해는 경남과 전남의 농촌지역에서 넓게 나타나고, 경제적 손실은 대규모의 도시와 공업이 발달된 경남해안지역에 집중되고 있다. 태풍재해의 규모를 저감시키기 위해서는 보다 정확하고 신속한 기상예보기술의 향상을 도모해야 함은 물론 홍수예방시설의 확충과 더불어 GIS 기법을 활용한 방재정보시스템에 기초하는 도시종합방재대책을 수립하도록 해야 할 것이다.

• Agrochemical news magazine
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• v.24 no.3 s.186
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• pp.6-9
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• 2003

• Korean journal of applied entomology
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• v.47 no.4
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• pp.395-400
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• 2008

Economic injury levels (EILs) and economic threshold (ET) were estimated for the two spider mite, Tetranychus urticae Koch (Acari, Tetranychidae) on greenhouse eggplants. T. urticae density increased until the mid-July and thereafter decreased in all plots where initial density of the mite were different each 0, 2, 5, 10 and 20 adults per plant was innoculated on June 7. Growth variables of were not different among experimental plots but fruit weights were lower in plots with higher initial mite density than in plots with lower initial mite density. Total number of fruits and the number of marketable fruits decreased in plots with higher initial mite density. The rates of yield loss increased with increasing initial mite density, resulting in 0, 3.9, 11.3, 14.5, 22.8% reduction in each of the above plots, respectively. The relationship between initial T. urticae densities and yield losses was well described by a linear regression, Y = 1.085X + 2.474, $R^2$ = 0.9659. Based on the relationship, the number of adults per plant which can cause 5% loss of yield was estimated to be approximately 1.8.