• Steel and Composite Structures
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• 제38권2호
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• pp.151-164
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• 2021

During the pipe forming process, a steel plate undergoes inelastic behavior multiple times under a load condition repeating tension and compression in the circumferential direction. It derives local reduction or increase of yield strength within the thickness of steel pipes by the plastic hardening and Bauschinger effect. In this study, a combined hardening model is proposed to effectively predict variations of yield strength in the circumferential direction of API-X65 and X70 steel pipes with relatively low t/D ratio during the forming process, which is expected to experience accumulated plastic strain of 2~3%, the typical Lüder band range in a low-carbon steel. Cyclic tensile tests of API-X65 and X70 steels were performed, and the parameters of the proposed model for the steels were calibrated using the test results. Bending-flattening tests to simulate repeated tension and compression during pipe forming were followed for API-X65 and X70 steels, and the results were compared with those by the proposed model and Zou et al. (2016), in order to verify the process of material model calibration based on tension-compression cyclic test, and the accuracy of the proposed model. Finally, parametric analysis for the yield strength of the steel plate in the circumferential direction of UOE pipe was conducted to investigate the effects of t/D and expansion ratios after O-forming on the yield strength. The results confirmed that the model by Zou et al. (2016) underestimated the yield strength of steel pipe with relatively low t/D ratio, and the parametric analysis showed that the t/D and expansion ratio have a significant impact on the strength of steel pipe.

• 한국토양비료학회지
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• 제5권1호
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• pp.33-39
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• 1972

벼의 생산능력을 높이기 위하여 진흥의 곡실 생산량을 기준하여 저위 (500kg/10a 이상), 중위 (600kg/10a 이상), 고위 (700kg/10a 이상)로 구분하고 이들벼의 군락조성 및 영양상태를 조사한 결과 1. 고위수량인 경우에는 출수후 엽면적이 크고 완만하게 줄어드는데 비해 저위수량인 경우는 엽면적이 급격히 감소하였다. 2. 고위수량인 경우는 저위수량인 경우에 비해 생육초기에는 투광율이 높고 생육후기에는 낮았으며 투광율대 엽면적비도 고위수량인 경우에서 높다. 3. 순동화량(N.A.R.)은 엽면적이 증가함에 따라 감소하였으며 저위수량인 경우에 비해 고위수량인 경우가 높았다. 4. 질소흡수량은 고위수량인 경우가 저위수량인 경우에 비해 절대 흡수량이 높고 흡수속도도 전생육기간을 통해 완만하며 저위수랑인 경우는 초기 질소흡수가 많고 출수기에 질수흡수를 종결하는데 비해 고위수량인 경우는 초기 흡수가 적고 출수후에도 상당량의 질소를 흡수하였다. 5. 출수기 전분축적량이 수확기 총생산량에 대하여 저위수량인 경우 40%인 반면 고위수량인 경우에는 약 10%로서 고위수량은 출수후 전분생산량에 의존도가 크다. 6. 수량구성요수중 이차생산능력인 곡실생산능력을 가장지배하는 인자는 등숙비율이였다.

• International Journal of Industrial Entomology and Biomaterials
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• 제4권2호
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• pp.143-147
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• 2002

Studies on the interrelationship between biological yield and harvest index, and their association with shoot rearing were carried out in 9 promising mulberry genotypes, which indicated significant variations among genotypes. Biological yield had close association with leaf yield components indicating that they are inter-related for higher productivity in mulberry, Biological yield revealed highly significant positive correlation with important leaf yield components. However height of the longest branch showed negative correlation with biological yield. Genotypes with higher biological yield associated with low ratio of stem weight to leaf weight and high Harvest index on dry weight basis are to be selected for shoot rearing. Biological yield recorded on fresh weight basis had less impact on the present study in comparison to dry weight basis.

• 한국연초학회지
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• 제12권2호
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• pp.91-101
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• 1990

A field experiment was conducted to find out the effects of field productivity, variety and nitrogen rate on the yield, quality, chemical constituents and physical properties of burley cured leaf in three field with different productivity(Degree of field productivity: A ; high, B ; medium, C : low) during successive two years(1988~89). The yield and quality were remarkably lowered when nitrogen fertilizer being applied much in low productive field. As compared with Burley 21, KB101 showed high yield, particularly the yield of KB101 in low productive field was relatively high. The effect of nitrogen rate on the yield was somewhat different according to field productivity and production year. When the nitrogen fertilizer being applied above 22.5kg/10a, the added nitrogen had no effect on the yield. Total nitrogen content of cured leaf grown in low productive field was high while total alkaloid was low, therefore total alkaloid/total nitrogen ratio was remarkably low. The lightness, red and yellow color of cured leaf grown in low productive field was remarkably low. As compared with Burley 21, the contents of total alkaloid and total nitrogen and shatter resistance index of cured leaf was somewhat low, while the filling power, lightness, red and yellow color were slightly high. Total nitrogen content of cured leaf was increased remarkably by nitrogen addition, but total alkaloid was not increased though the nitrogen fertilizer being applied above 22.5kg/10a. The filling power and shatter resistance index of cured leaf grown in high nitrogen plot, and the lightness and yellow color were low while the red color was relatively high. It comes into question that the visual quality being increased as well as increment of yield and nitrogenous compounds by nitrogen addition in high productive field. In low productive field, it is considerable that nitrogen addition for high yield should be prohibited because it causes the decrement of yield and quality, on the contrary.

• 한국산림과학회지
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• 제99권4호
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• pp.479-486
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• 2010

당해년도 송이 생산량 추이와 가격 예측을 위하여 수매되는 송이의 일자별 생산량과 품질등급의 관련성을 분석하였다. 2000년부터 2008년까지의 9년간 영덕군 산림조합의 수매자료를 분석한 결과, 송이 수매량 변화와 각 품질등급이 차지하는 비율은 극심한 가뭄과 이상기온 등 특이한 해를 제외하면, 고급품(1등급과 2등급) 송이는 초기에 50%를 넘는 비율을 차지하다가 점차 줄어드는 모습을 나타낸 반면, 저급품(개산품, 파손품 및 벌레 먹은 것 등)의 경우에는 수매량이 정점을 이룬 이후에 지속적으로 그 비율이 증가하는 것으로 나타났다. 송이 수매량이 정점에 도달하기 1~9일 전에 고급품의 비율과 저급품의 비율이 반전되었으며, 이를 통하여 고급품 송이에 비하여 개산품의 비율이 많아지면 조만간 송이 생산량이 줄어들게 됨을 예측할 수 있었다. 고급품 송이가 차지하는 비율은 전체 수매량의 패턴과 비슷하지만 3~4일 정도 앞서 나가는 모습을 보여주고 있었으며, 매일의 송이 수매량은 3~4일 전의 고급품 수매량과 0.5 이상(3일전의 상관계수는 0.51, 4일전은 0.54)의 상관관계를 나타내었다. 따라서 송이 수매품의 품질등급 분포 검토를 통해 예측하는 해당 시점 이후의 송이 생산량 추이(증가 또는 감소 여부)를 예측할 수 있다고 판단되었다. 또한, 고급품 송이 가격은 수매량과 반비례하는 관계가 뚜렷하게 나타난다. 따라서 송이 수매량 추이는 송이 가격변화를 예측할 수 있는 정보를 제공하게 되므로 송이 유통에서도 중요한 역할을 할 수 있음을 알 수 있었다.

• Asian-Australasian Journal of Animal Sciences
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• 제9권4호
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• pp.411-420
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• 1996

Asia Triple HIn this study an attempt was made to determine the cost of producing fodders at Savar Dairy Farm (SDF). For this purpose, all seasonal fodders, such as Maize, Jowar, Cowpea and Oat and all perennial fodders, such as Para and Napier were studied. The highest acreage of land was allocated to high-land Para (33.8%) and the lowest acreage (2.7%) was devoted to Cowpea. Jowar attained the highest yield (74.2 tons) per hectare and Maize attained the lowest yield (25.8 tons/h). The highest cost per hectare was attributed to Jowar (TK. 20944.18) while the lowest cost was attributed to low-land para (TK. 10349.86). The cost of production of fodder per kilogram was the highest (TK. 0.66) for Maize and the lowest for Oat (TK. 0.24). The cost of production of low-land Para was much lower than that of high land Para. The per kilogram cost of silage production was the highest (TK. 0.71) for Maize and the lowest (TK. 0.31) was for Napier. The gross return analysis further showed that the highest net margin and B:C ratio were observed for Napier followed by Low-land Para, Jowar, Oat, Cowpea, High-land Para and Maize. Therefore, those fodders whose B:C ratios and yield/ha were higher should be allocated more area of land to stimulate increased returns to SDF in the future is suggested.

• Plant Resources
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• 제5권2호
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• pp.104-108
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• 2002

In order to obtain basic information for selecting early maturing rice varieties which is suitable for early cropping before Alisma plantago in the southern part of Korea. Six rice varieties were grown from May to August in 2002 at Youngjeon Experiment Field, Sunchon and yield components and yield of plants were investingated. Early maturing rice cv. Grubyeo showed higher rough rice yield than any other varieties used in the experiment. It showed high yield components, such as culm length, panicle length, number of panicles per plant, number of spikelets per panicle and ratio of ripened grains. Therefore, it was concluded that Grubyeo was the most suitable variety with high yield for the cultivation before growing of Alisma plantago at the southern part of Korea. The heritability of culm length number of spikelets per panicle and rough rice yield were high and that of panicle length number of panicle per plant, ratio of ripened grain and 1,000 grain wt. of milled rice were low. According to the result of path coefficient analysis, characters highly correlated with rough rice yield showed large direct effects on rough rice yield.

• 펄프종이기술
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• 제37권5호통권113호
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• pp.41-49
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• 2005

This paper deals the effect of anthraquinone (AQ) on the contribution of sulphidity in kraft pulping of sapwood. The pulping conditions namely- active alkali concentration, pulpingtime, temperature and liquor ratio were varied in low ($15\%$) and high ($30\%$) sulphidity. $0.1\%$ AQ was added in the low and high sulphidity pulping with varying active alkali concentration and cooking time. At optimum conditions, low sulphidity kraft process produced about $44\%$ pulp yield with kappa number of about 23. But in high sulphidity kraft process kappa number was reduced to about 20 at the same yield. An addition of AQ reduced alkali requirement by $2\%$ on oven dried raw material and cooking time by 1 hour to produce pulp yield of about $44\%$ at kappa number 20. AQ is more effective in low sulphidity pulping than the high sulphidity pulping. The breaking length of kraft-AQ pulp was slightly higher than that of kraft pulp.

• 콘크리트학회논문집
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• 제17권5호
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• pp.843-852
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• 2005

Presently, test results and stress-strain models for poorly confined high-strength columns, more specifically for columns with a tie volumetric ratio smaller than $2.0\%$, are scarce. This paper presents test results loaded in axial direction for square reinforced concrete columns confined by various volumetric ratio lateral ties including low-volumetric ratio. Test variables include concrete compressive strength, tie yield strength, tie arrangement type, and tie volumetric ratio. Local strains measured using strain gages bonded to an acryl rod. For square RC columns confined by lateral ties, the confinement effect was efficiently improved by changing tie arrangement type from Type-A to Type-B. A method to compute the stress in lateral ties at the concrete peak strength and a new stress-strain model for the confined concrete are proposed. Over a wide range of confinement parameters, the model shows good agreement with stress-strain relationships established experimentally.

• 한국농림기상학회:학술대회논문집
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• 한국농림기상학회 2011년도 학술발표회
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• pp.16-18
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• 2011

Evaluation of climate change on the rice productivity was conducted using crop growth simulation model, where Odae, Hwaseong, Ilpum were used as a representative cultivar of early, medium, and medium-late rice maturity type, respectively, and climate change scenario 'A1B' was applied to weather data for future climate change at 57sites. When cropping season was fixed, rice yield decreased by 4~35% as climate change which was caused by poor filled grain ratio with high temperature and low irradiation during grain-filling. When cropping season was changed, rice yield decreased by only 0~5% as climate change which was caused poor filled grain ratio with low irradiation during grain-filling period. However, this irradiation decline was less than when cropping season was fixed. Therefore, we need to develop rice cultivars resistant to low irradiation which can maintain high filled grain ratio under poor irradiation condition, and late maturity rice cultivars whose growing period is longer than the present medium-late maturity type.