• Journal of Biosystems Engineering
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• 제18권4호
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• pp.344-350
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• 1993

The purpose of this study is to develop design equations to calculate optimum specifications and dimensions such as weight, engine horsepower, etc. of the tractor necessary to perform stable rotary tillage. The main results of this study are as follows. 1. A wheel-lug ought to receive a special resistance in downward direction which resists the lug's upward motion on wet sticky soil surface. The authors introduce a new academic name of the "lift resistance(上昇抵抗力, 상승저항력)" for such a force which resists retraction of a wheel lug from the soil in the upward trochoidal motion. This force is composed of the frictional force acting on the trailing and the leading lug side, and the "perpendicular adhesion(鉛直付着力, 연직부착력)" acting on the lug face and the undertread face on adhesive soil. 2. The "lift resistance ratio(上昇抵抗力係數, 상승저항력계수)" and the "perpendicular adhesion ratio(鉛直付着力係數, 연직부착력계수)" were defined, which are something similar to the definition of the motion resistance ratio, the traction coefficient, etc. 3. The design equation of the optimum weight of a rotary tiller mounted on the tractor derived by calaulating the forces acting on the rotary blades. 4. The design equations to calculate optimum specifications and dimensions such as weight, engine horsepower, etc. of the tractor necessary to perform stable rotary tillage were derived. It becomes clear that the optimum weight of a rotary tiller and a tractor can be estimated in planning design by means of putting about 21 design factors of the target into the equation. These equations are useful for planning design to estimate the optimum dimensions and specifications of a rotary tiller as well as a tractor by the use of known and/or unknown design parameters.

• 농업과학연구
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• 제24권2호
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• pp.237-241
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• 1997

교잡종 찰옥수수에서 발생하는 분얼 제거 처리가 주경의 첫째이삭의 크기에 미치는 효과를 알아 보고자 생육 과정별로 분얼을 제거한 결과, 분얼 초기에 분얼경을 제거하는 것이 간장이 가장 컷고, 다음은 분얼성기, 무처리순으로 나타났으나 이들 처리간에 유의차는 인정되지 않았는데, 착수고 역시 간장과 비슷한 경향이었다 경태의 경우 분얼초기, 분얼성기, 무처리, 웅수출현기 순으로 높게 나타났으며, 이들 처리간에는 고도의 유의차가 인정되었다 주경 제1 이삭절의 엽장은 분얼초기, 분얼성기, 웅수 출현기, 무처리 순으로 높게 나타 났으며 엽폭 역시 엽장과 비슷한 경향으로 처리간에 고도의 유의차가 인정 되었다. 주경 제1 이삭의 길이는 분얼초기에 처리한 구에서 가장 컷고, 다음이 분얼 성기, 웅수 출현기, 무처리 순으로 높게 나타났다. 이삭직경 역시 이삭 길이와 동일한 경향으로 이들 처리간에는 매우 현저한 유의차가 인정되었다.

• 생명과학회지
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• 제10권2호
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• pp.177-181
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• 2000

This study was conducted to estimate the genetic parameters such as combining ability, heritabilities and correlation coefficients forsome agronomic characters by 6$\times$6 dialled crosses of barley. The results obtained were summarized as follows. Mean squares of general combining ability(GCA) and specific combining ability(SCA) were significant for all characters observed. Mean squares of general combining ability for all characters were expressed as higher values than those of specific combining ability. Jecheon #5 showed the high general combining ability effects for culm length, and Waegwanpimack #1 showed the highest general combining ability effects for tiller number. Cygne also showed the high general combining ability effects for spike length and 1,000 grains weight. Furthermore, Plumage was expressed with the highest general combining ability effects for spike length and 1,000 grains weight. Furthermore, Plumage was expressed with the highest general combining ability effects for number of grains per spike. In specific combining ability effects, Samdugjeonbug # 45$\times$Plumage showed the high value for culm length, and Suwon #6 $\times$Waegwanpimack #1$\times$ was expressed with the highest specific combining ability effects for tiller number. Jecheon #5$\times$Plumage also showed the high specific combining ability effects for spike length and number of grains per spike. Suwon #6$\times$Cygne showed the high specific combining ability effects for 1,000 grains weight. The heritabilities of spike length an number of grains per spike were over 90%. In correlation coefficients among characters, relationships between culm length and tiller number, culm length and spike length, culm length and 1,000 grains weight, and spike length and 1,000 grains weight showed highly positively correlation.

• Journal of Biosystems Engineering
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• 제25권5호
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• pp.369-378
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• 2000

The purpose of this study is to developed high-efficient rotary tillage system for a power tiller by improving the rotary blade. A kind of the rotary blade with single-edged blade(DS) was developed that requires lower tillage energy than conventional double-edged blade(CD) on the design theory for Japanese rotary blade. In order to find out the tillage characteristics between the single-edged blade and the double-edged blade for power tiller, experiments were performed in soil-bins which were filled up clay loam, loam and sandy loam, and then analyzed the effects of the factors such as soil texture, travelling speed, rotational speed, and tillage depth to each of the blades. And field tests were carried out to compare tillage performances of the two blades using rotary cultivator driven by conventional power tiller. The results of this study were summarized as follows; 1) On the soil bin experiment, it was found that tillage torque of the single-edged blade was less than the ones of the double-edged blade. The decreasing ratios of maximum tillage torque of the single-edged blade to the ones of the double-edged blade were 1 to 8% at clay loam, 5 to 20% at loam and 9 to 31% at sandy loam, respectively. 2) By the field tests, that the tillage performances with the single-edged blade compared with the double-edged blade was improved about 19% in field capacity, about 34% in fuel consumption, and 12.5% in soil breaking ratio. Furthermore, the fluctuation of engine speed, the variation of exhaust gas temperature, and the amount of soil clogging on the blade and straw wound on the rotary shaft showed lower values with the developed blade than the conventional blade. So, it may be concluded that tillage performance by the developed single-edged blade was improved compared with the one by the conventional double-edged blade.

• 식물병연구
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• 제9권1호
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• pp.52-56
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• 2003

전남 나주의 벼 누른오갈병이 발생한 담수직파 포장에서 일미벼를 대상으로 병 발생이 벼 생육에 미치는 영향을 조사하고 품종저항성 검정을 수행하였다. 누른오갈병 발생시 잎에는 퇴록반점이 나타나고 엽장이 짧아지며 벼의 생육이 진행되면서 줄기의 절간신장이 제대로 이루어지지 않아 마디사이가 기형적으로 자라고 출수가 안되거나 기형이삭이 되는 증상을 보였다. 벼 누른오갈병 이병시 초장이 짧아졌고, 분얼수는 최고분얼기 전에 발병주가 적었지만 그 이후에는 발병주가 많았다. 마디수는 발병줄기가 건전줄기에 비해 많은 반면에 마디길이는 짧았다. 발병정도가 심할 수록 단위면적당 이삭수가 적고 등숙율이 낮아 수량이 크게 감소하였다. 유묘를 대상으로 품종 저항성 검정을 실시한 결과, 동진벼, 계화벼가 벼 누른오갈병에 대해서 저항성이었다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 추계학술대회
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• pp.135-135
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• 2022

For abnormal weather disaster and building constructions, the shading stress could occur in crops more often. Those shading stress can effect on rice growth characters. Therefore, we investigated the shading effect on rice growth characters. Shading treatments were treated using shading screen as 35, 55, 75 and 100%. To check the shading effect on rooting after transplanting, shading stress treated after transplanting for 20 days as 35, 55 and 75%, And 35, 55, 75 and 100% of shading were treated 60 days after transplanting to check the growth characters. After transplanting, the shading stress effected on leaf and root growth. At 19 days after transplanting, leaf number reduced by shading stress. In 35, 55 and 75% shading stress, the leaf number reduced as 0.38, 0.45 and 0.9 respectively compared to control treatment. And root length was also reduced as 0.39, 0.6 and 1.93 cm respectively compared to control treatment. The plant height was slightly increased in 35 and 55% and reduced in 100%. Leaf growth speed per day was reduced as 0.0167 according to shading stress. And root growth speed also reduced as 0.0426 according to shading stress. The shading stress during vegetative stage effected on plant height and tiller number. In 35, 55 and 75% of shading stress, the plant height was slightly increased but it was reduced in 100%. Tiller number was significantly reduced by shading stress. According to 10% of shading stress, about 7% of the tiller number was reduced. However, leaf color did not change by the shading stress. The leaf area in 2^nd to 4nd leaf from new leaf reduced as 297 and 1044 in 75 and 100% of shading stress and increased as 70 and 99 in 35 and 55%. These leaf area change was affected by both the length and width of the leaf.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 추계학술대회
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• pp.13-13
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• 2022

Recently, stable crop production is threatened by the effects of climate change. In particular, it is difficult to consistently maintain agricultural policies due to large price fluctuations depending on the difference in total domestic rice production from year to year. For stable rice production amid changes in the crop growing environment, development of varieties with improved disease resistance and abiotic stress stability is becoming more important. In here, drought and cold tolerant trait have been studied. First, for the development of drought tolerant varieties, we analyzed which agricultural traits are mainly affected by domestic drought conditions. As a result, it was observed that drought caused by the lack of water during transplanting season inhibits the development of the number of tiller and reduces the yield. 'Samgang' was selected as a useful genetic resource with strong drought tolerant and stable tiller number development even under drought conditions by phenotype screening. Three of drought tolerant QTLs were identified using doubled haploid (DH) population derived from a cross between Nacdong and Samgang, a drought sensitive and a tolerant, respectively. Among these QTLs, when qVDT2 and qVDTl1 were integrated, it was investigated that the tiller number development was relatively stable in the rainfed paddy field conditions. It is known that the high-yielding Tongil-type cultivars are severely affected by cold stress throughout the entire growth stage. In this study, we established conditions that can test the cold tolerance phenotype with alternate temperature to treat low temperatures in indoor growth conditions similar to those in field conditions at seedling stage. Three cold tolerant QTLs were explored using population derived from a cross between Hanareum2 (cold sensitive variety, Tongil-type) and Unkwang (cold tolerant variety, Japonica). Among these QTLs, qSCT12 showed strong cold tolerant phenotype, and when all of three QTLs were integrated, it was investigated that cold tolerant score was relatively similar to its donor parent, Unkwang, in our experimental conditions. We are performing that development of new variety with improved cold tolerant through the introduction of these QTLs.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 추계학술대회
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• pp.63-63
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• 2022

Wheat flour can be categorized into bread, all-purpose, cake flour according to its protein content. Since optimal wheat flour protein content is different for each end use, it is necessary to diversify the nitrogen fertilizer methods depending on the end use and cultivar. Optimal wheat flour protein content of soft wheat (for cake flour) is lowest (<=10%) among all end use, it is necessary to develop nitrogen fertilizer methods for high yield and low protein content. In order to analyze the yield and quality changes of soft wheat as nitrogen fertilizer amount and splitting timing, soft wheat cultivar 'goso' was sown on paddy soil in jeunju, Republic of Korea ('21.10). the amount of nitrogen fertilizer was divided into 4 levels by adjusting 2kg/10a increments from 5.1 to ll.lkg/lOa, and in the N 7.1 and 9.1 kg/1 Oa(standard) treatment, N amount divided into sowing date:regrowing stage=3:7,4:6(standard), 5:5. In regrowing stage, Tiller number and N fertilizer amount at sowing date showed a correlation; y=-121.14x²+792.66x-525.41 (R²=0.77^*, y: Tiller number/m², x: N amount at sowing date(kg/10a)). Tiller number in regrowing stage was the highest when the nitrogen fertilizer amount at sowing date was 3.23kg/10a. spike number per m² was the highest when N fertilizer was divided into sowing date:regrowing stage=3:7(N amount: 9.1kg/10a). If N fertilizer amount was fixed, grain yield was also the highest when N fertilizer was divided into sowing date :regrowing stage=3:7. Also, N amount at sowing date and grain yield showed no correlation, but N amount at regrowing stage and grain yield showed significant correlation. As N amount increased, protein content also showed a tendency to increase.

• 한국작물학회지
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• 제69권1호
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• pp.15-24
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• 2024

Environmental factors play an important role in crop growth and development. In recent years, climate change has become a challenge that limits environmental factors. Light is an important environmental factor for photosynthesis in rice. In addition, temperature is one of the most important factors for rice production; thus, a 1℃ increase in temperature because of climate change can affect rice growth and development. Therefore, we investigated the effect of shading on the growth characteristics of rice under different temperature conditions from the vegetative stage to the flowering stage. Plants were grown at three different temperatures: 26℃/16℃ for 21℃, 29℃/19℃ for 24℃, and 22℃/32℃ for 27℃ in a phytotron. A 55% shade treatment was applied after 10 days of transplanting until the flowering stage. Plant height was not affected by the shading treatment. In the maximum tiller number response to shading, a lower tiller number and growth speed of tiller was found in the 27℃ condition. Among leaf characteristics, shading increased the flag leaf area, length, width, and effective leaf area; however, it decreased the leaf number on the main stem, especially at 27℃. In terms of stem characteristics, shading affected culm wall thickness in both varieties. Finally, regarding the panicle characteristics, lower panicle numbers, spikelet numbers per panicle, primary numbers, and secondary numbers per panicle were found under the shading treatment. Most of the desirable characteristics were affected by the shading treatment at 27℃. Overall, these results indicated that shading had a greater effect on rice plant growth at high temperature.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.91-91
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• 2017

Drought is the most serious abiotic stress limiting rice production. However, little progress has been made in the genetic analysis of drought tolerance, because it is a complex trait controlled by a number of genes and affected by various environmental factors. In here, we screened 218 rice genetic resources for drought tolerance at vegetative stage and selected 32 highly drought tolerant varieties in greenhouse. Under rain-fed conditions, Grain yield of Nagdong was decreased by 53.3% from 517 kg/10a to 241 kg/10a when compare to irrigation condition. By comparison, grain yield of Samgang was decreased by 23.6% from 550 kg/10a to 420 kg/10a. The variety Samgang exhibited strong drought tolerance and stable yield in rain-fed conditions and was selected for further study. To identify QTLs for drought tolerance, we examined visual drought tolerance (VDT) and relative water content (RWC) using a doubled haploid (DH) population consisted of 101 lines derived from a cross between Samgang (a drought tolerance variety) and Nagdong (a drought sensitive variety). Three QTLs for VDT were located on chromosomes 2, 6, and 11, respectively, and explained 41.8% of the total phenotypic variance. qVDT2, flanked by markers RM324 and S2016, explained 8.8% of the phenotypic variance with LOD score of 3.3 and an additive effect of -0.6. qVDT6 was flanked by S6022 and S6023 and explained 12.7% of the phenotypic variance with LOD score of 5.0 and an additive effect of -0.7. qVDT11, flanked by markers RM26765 and RM287, explained 19.9% of the phenotypic variance with LOD score of 7.1 and an additive effect of -1.0. qRWC11 was the only QTL for RWC to be identified; it was in the same locus as qVDT11. qRWC11 explained 19.6% of the phenotypic variance, with a LOD score of 4.0 and an additive effect of 9.7. To determine QTL effects on drought tolerance in rain-fed paddy conditions, seven DH lines were selected according to the number of QTLs they contained. Of the drought tolerance associated QTLs, qVDT2 and qVDT6 did not affect tiller formation, but qVDT11increased tiller number. Tiller formation was most stable when qVDT2 and qVDT11 were combined. DH lines with both of these drought tolerance associated QTLs exhibited the most stable tiller formation. These results suggest that qVDT11 is important for drought tolerance and stable tiller formation under drought stress condition in field.