• 한국토양비료학회지
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• 제48권5호
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• pp.477-484
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• 2015

Environmental effect of water-saving irrigation on the emissions of greenhouse gases (GHGs) has not been well investigated. The objective of this study was to measure the effect of water-saving irrigation on GHGs as well as water use and rice production yield in paddy field condition in Korea. Four experimental runoff plots of 4x35 m in size were prepared at an existing paddy field. GHGs emission was measured during the 2012~2013 growing seasons while a Japonica rice variety was cultivated. Four different water management methods, 1) Continuous Flooding (CF), 2) Intermittent Drainage (ID), 3) Water Saving (WS), and 4) CF+WS, were used during a rice growing season to compare the effects of water management methods on GHGs emission. CF method is flooding all the time, ID method makes paddy water drained 40 days after transplanting for about two weeks, WS method maintains 2~3 cm water-level, which should be refilled when the water-level decreased to about 0 cm, and CF+WS method combines CF method before 30 days after transplanting (DAT) and WS method after 30 DAT. Regardless of water management methods, paddy field water was drained about 30 days before harvest. Amount of GHGs emission from WS plot was reduced by 69.3% compared to that from CF plot and by 59.0% compared to that from ID plot. Amount of GHGs emission from CF+WS plot was reduced by 60.7% compared to that from CF plot and by 47.5% compared to that from ID plot. Weed occurrence in CF+WS plots was reduced to 62.2% in comparison with the WS plot, implying that CF+WS plot showed the best effect to mitigation of the greenhouse gas emission in the atmosphere.

• 한국농공학회논문집
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• 제62권4호
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• pp.63-73
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• 2020

The area of paddy fields for upland crop cultivation is gradually increasing. In this context, we developed a chain type mole drainer that can be attached to a tractor to prevent the wet injury of crops. To conduct a field test, we formed underdrains at 2 m intervals in a paddy field wherein soybeans are cultivated, and we investigated the status of the soil moisture, groundwater level, and soybean growth during the cultivation period. The soil moisture content decreased by 22.3~26.8% in the test plot and by 5.9~6.9% in the control plot during a period of 57~88 hour after a rainfall of 41.5~157.0 mm. The effect of underdrainage was clear as the hourly groundwater level decreased approximately 2.8 times faster in the test plot compared with the control plot. Moreover, the soybean yield was greater by 78.6 kg/10a in the test plot than in the control plot. Therefore, for soybean cultivation in paddy fields, the use of the developed mole drainer is expected to help in improving the drainage and increasing the soybean yield.

• 대한기계학회논문집B
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• 제32권1호
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• pp.62-69
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• 2008

A post-processing program based on the OOP(Object-Oriented Programming) concept has been developed for flow visualization of the flow analysis code(PowerCFD) using unstructured cell-centered method. User-friendly GUI(GTaphic User Interface) has been built on the base of MFC(Microsoft Foundation Class). The program is organized as modules by classes including those based on VTK(Visualization ToolKit)-library, and these classes are made to function through inheritance and cooperation which is an important and valuable OOP concept. The major functions of this post-processor program are introduced and demonstrated, which include mesh plot, contour plot, vector plot, surface plots, cut plot, clip plot, xy-plot and streamline plot as well as view manipulation (translation, rotation, scaling etc).

• 미생물학회지
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• 제24권2호
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• pp.184-193
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• 1986

Interrelation between environmental influences on soil microorganisms and it's effect on disease development in ginseng (Panax ginseng C.A. Meyer) field were studied to obtain a preventive measures against the root rot of ginseng caused by soil-borne pathogens in soil in three major Korean ginseng producing areas such as Kumsan, Goesan and Poonggi. Populations of actinomycetes were relatively high in fall season from September to November. Their numbers were highly populated in healthy plot in field than replanted disease field of ginseng, whereas ratio of Trichoderma spp to actinomycetes increased in healthy plot of field indicating the higher numbers of Trichoderma spp pressented in healthy plot field. The numbers of propagules of Trichoderma spp generally increased in early summer through early fall season. Their numbers were also highly populated in the healthy plot of fields. The contents of organic matter and phosphate in healthy plot of field were somewhat high, and phophate/organic matter ratio and Mg content were high in diseased replanted field. All of the soil samples showed a weak acidic pH from 4.5 to 4.7. Soilmoisture content was increased during winter season and it did not show any significant changes curing the growing period, showing 24.6% in healthy plot in field and 19.5% in deseased plot in field respectively. Soil temperature was highest in July and August and lowest in January and February.

• 한국산림과학회지
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• 제96권2호
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• pp.151-159
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• 2007

This study was conducted to investigate the effects of thinning on changes in stand characteristics and understory vegetation in a silvopasture practiced Japanese larch plantation in the Research Forest of Kangwon National University, Korea. Three different thinning intensities (64%, 35%, and control) were applied. Before and after thinning, the understory plant species increased its number from 48 (7 tree species, 7 shrubs species, 28 herbaceous species, and 6 woody climbers) to 100 (11 tree species, 15 shrub species, 67 herbaceous species, and 7 woody climbers). Thinning made plants invade easily on the forest floor, and plot A (325 stems/ha) had much higher number of undersory species than those Of plot B (575 stems/ha) and control plot (1,150 stems/ha). In three years after thinning, understory aboveground biomass (kg/ha) of herbs were 523 for control, 1,230 for plot B, and 1,288 for plot A. The canopy coverage had remarkable influence on the understory biomass production, resulting in relatively small amount of herbage production on control plot. The differences were statistically significant between thinned plots and unthinned plot, but there were no significant differences among the thinned plots (p<0.05).

• 한국환경농학회지
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• 제42권2호
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• pp.93-103
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• 2023

Persistence and degradation patterns of acequinocyl and its metabolite, hydroxyl-acequinocyl (acequinocyl-OH) and fenpyroximate in butterburs (Petasites japonicus Max.) were investigated after pesticide application. Butterburs, one of the minor crops in South Korea, was planted in two plots (plot A for double and plot B for single application) in a greenhouse. Butterburs samples were also planted in a separate plot without pesticide treatment, as the control. A commercial pesticide containing acequinocyl and fenpyroximate was applied to the foliage of butterburs at hourly intervals after dilution. Recoveries of acequinocyl and acequinocyl-OH were 78.6-84.7% and 83.7-95.5%, respectively; the relative standard deviation of the two compounds were less than 5%. The method limit of quantification was 0.01 mg/kg. The total (Ʃ) acequinocyl residues in butterburs reduced by 96.0% at 14 days and 75.9% at 7 days, in plot A and B, respectively, after final pesticide applications. The biological half-life (DT₅₀) of Ʃ acequinocyl and fenpyroximate, calculated using the dissipation rate, was 3.0 days and 4.0 days, respectively. These data were used to set up maximum residue and safe standard levels when the pesticides are applied to control pests during butterbur cultivation. Risk assessment results showed that the maximum % acceptable daily intake was 7.74% for Ʃ acequinocyl and 0.16% for Ʃ fenpyroximate. The theoretical maximum daily intake of Ʃ acequinocyl and fenpyroximate was 26.3% and 35.8%, respectively. In conclusion, the concentrations of Ʃ acequinocyl and fenpyroximate in butterburs pose no significant health risks to Koreans.

• 한국토양비료학회지
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• 제46권6호
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• pp.599-605
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• 2013

The effects of water-saving irrigation on the emissions of greenhouse gases and the prokaryotic communities in rice paddy soils were investigated through a field experiment. In the Water-Saving (WS) irrigation, the water layer was kept at 2~3 cm while it was kept at 6 cm in the Continuousiy Flooding (CF) irrigation. A plot was treated with Intermittently Drainage (ID) that is drained as fine cracks on the floor were seen after transplanting. GHGs emission amounts from WS plots were reduced by 78.1% compared to that from CF plot and by 70.7% compared to that from ID plot, meaning that WS could help contribute to mitigation of the greenhouse gas accumulation in the atmosphere.

• 한국토양비료학회지
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• 제29권1호
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• pp.15-19
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• 1996

유수형성기(幼穗形成期) 전에 한발피해를 입은 벼에 대한 피해경감을 위하여 질소와 카리비료 시용과 관수(灌水) 처리로 벼 수량에 미치는 영향을 시험한 결과는 다음과 같다. 1. 벼의 수량(收量)은 정상구에 비해 질소 30~60 kg/ha시용구는 90~95%. 카리 시용구는 87% 수준이었으며, 대조구는 정상구 수량의 86% 수준이었다. 관수(灌水)만한 대조구에 비해 한발피해를 입은 무비무관수(無肥無灌水)의 수량(收量)은 34%에 불과하였다. 2. 한발피해시 대조구에 비해 관수(灌水)와 동시 질소 30~60 kg/ha 시용으로 각각 수량(收量) 이 5. 10% 증수(增收)되었고, 질소 60kg/ha처리구는 5% 수준에서 유의성이 인정되었다. 출수기(出穗期)는 정상구에 비해 질소 시용구가 3일(日), 카리 시용구가 4일(日), 대조구가 8일(日) 정도 늦었다. 3. 한발피해를 입은 벼의 수량 확보를 위한 방법으로 관수(灌水)를 하는 것이 효과가 컸으며, 카리시용보다 질소시용이 효과가 있었다.

• 한국작물학회지
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• 제51권spc1호
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• pp.52-57
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• 2006

벼 담수직파재배에서 입모수가 적정입모수(120개/$m^2$)보다 적은 과소구를 60개/$m^2$, 적정입모수보다 많은 과다구를 200개/$m^2$로 설정하여, 과소구의 경우 3엽기에 4 kg/10a의 질소를 추가 시비하여 분얼발생을 촉진시키고 과다구에서는 5엽기에 시용하는 분얼비 3.3 kg/10a의 질소시비를 생략하여 분얼을 억제한 결과는 아래와 같다. 1. 개체별 최고분얼수는 적정구가 9.8개인데 비하여 과소구는 15.2개, 과다구는 8.6개이었으며, 개체별 유효분얼수는 적정구가 3.7개, 과소구가 6.5개, 그리고 과다구가 2.4개로 입모가 과다할수록 개체당 분얼수가 줄어들고 유효경비율이 낮아졌다. 2. 분얼발생 양상은 입모밀도에 관계없이 주간 3절위에서 첫 번째 1차 분얼이 발생하였으며, 유효분얼은 과소구, 적정구, 과다구에서 각각 6.5개/plant, 3.7개/plant, 2.4개/plant 발생하였다. 3. 입모과소구의 벼 개체내에서 분얼의 발생 순서와 간장, 수장, 무효분얼수, 수당립수, 임실율은 부의상관관계가 있었으나, 적정 입모밀도에서는 유의한 상관이 없었다. 입모과다구에서는 분얼발생순서와 수장, 무효분얼, 완전미율이 유의한 상관관계를 나타내었다. 4. 현미외관 특성은 입모 과소구가 적정구나 과다구 보다 청미발생이 적어서 완전미율이 가장 높게 나타났으며, 과다구와 적정구의 경우에는 1차 분얼에서 청미발생이 과소구보다 15-20%정도 높게 나타났다. 5. 쌀 수량은 적정구가 494 kg/10a인데 비하여 과소구는 적정구의 99%, 과다구는 적정구의 97%의 수량이 확보되었다.

• 한국초지조사료학회지
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• 제9권2호
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• pp.68-76
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• 1989

The effect of characteristic of mixture sowing combination on the development of botanical composition was conducted for 12 years on the meadow experiment. The results of this study were summarized as follows. 1. Festuca pratensis lost the expected position of a dominant species. Its vegetation ratio decreased gradually until the last survey year. 2. Arrhenatherum elatius, known as a typical 2-cutting grasss, developed to a dominant species only in the 3- cutting plot without limitation. 3. Alopecurus pratensis, whose feeding value diminishes rapidly, developed to a dominant species regardless of N-fertilization under the condition of 3-cutting, even though the same small amount of seeding was introduced as usual. 4. Trisetum flavescens which causes calcinose exceeded the 40% of vegetation ratio which was the approved rate for feeding at the high N-level (2OOKgIha). 5. Among the introduced, the species showed the significance in quantity were Lotus corniculafus solely in the 2-cutting plot, and Trifolium repens solely in the 3-cutting plot. In the 3-cutting plot legume yet remained under N-fertilization. 6. The appropriate ratio of vegetation for the subordinate species in the mixture sowing combination was easily attained from the least amount of seeding (Gramineae with max. 3Kg/ha, Leguminosae with max. 2kgIha). 7. Into the mixture sowing combination, infiltrated unintroduced species marked more noticeably in the 2- cutting plot than in the 3-cutting plot.