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        검색결과 257

        46.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this theoretical study, a design and performance analysis theory of a micro flowrate and high pressure air-compressor is developed. The governing equations are from the gas state equation and fluid dynamic theories because the working fluid in the air compressor is in a gas phase. A case study was conducted to design a reciprocating type of air compressor which the target performance was 0.6liter/min in the volume flowrate with 5atg in air pressure at 1,600rpm rotational speed. Geometrical size of the model air compressor designed is 10mm in stroke, 20mm in bore with 4.79 compression ratio. From the performance analysis of the model compressor, it was found that the air volume flowrate produced was 0.6liter/min with 5.81atg in pressure. The design theory of a micro-size high-pressure air compressor developed in this study is expected to be very useful design tools in NANO technology industry.
        4,000원
        47.
        2019.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This experiment was carried out to study the change of productivity and feed value in different types of hilly pasture. The pasture utilized in the experiment was placed on the experimental farm of Pyeongchang Campus of Seoul National University. Forage production type(FP; Orchardgrass 18 + Tall Fescue 12 + Timothy 5 + White clover 5 kg/ha) and Public farm type(PF: Orchardgrass 12 + Tall Fescue 18 + Timothy 5 + White clover 5 kg/ha) pasture were established in September 3, 2014 and utilized (cutting or grazing) four times every year. Growth characteristics, yield and forage quality were investigated for two years. Plant height of grasses was the highest in the 1st cutting and legumes was in the 2nd cutting. Dry matter (DM) content was highest at every the 1st cut grasses significantly lower at the 2nd harvest (p<0.05). However, there was no significant difference in the 2nd, 3rd and 4th harvest in 2016. In the botanical composition change, the portion of legume was gradually increased after pasture establishment and the ratio of weed and bare land was higher at 2nd and 3rd cutting, but it was decreased at 4th harvest. There was no significant difference in 2016 of fresh yield between two farm types (p>0.05). The yield of dry matter showed similar trend of fresh yield and forage production type was higher than that of public farm type (p<0.05). The forage intake by livestock was 1,452 kg/ha in 2015 and 1,743 kg/ha in 2016. Pasture utilization ratio of public farm type pasture was highest in the 3rd grazing time. Forage quality of pasture in relation to management type had not significant difference, but there was difference in harvest times. Crude protein (CP) was the lowest in the 1st harvest and total digestible nutrient (TDN) was highest in the 1st harvest and lowest in the 4th harvest. Based on the above results, it is found that the establishment of pasture suitable for farm’s situation is important for set up of Korean model of hilly pasture. Although the forage production type is superior on forage productivity, it is recommended that the results will be provided as basic data for management of public farm type in the future.
        4,000원
        48.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        동계작물인 보리를 재배한 후 하계작물인 수수, 기장 및 피를 대상으로 하여 조사료 생산량과 그에 따른 사료가치를 분석하여 보리와 적합한 하계작물의 최적의 작물조합을 선정하기 위하여 실시한 결과 다음과 같다. 1. 초장은 하계작물 모두 1차 및 2차 수확할 때보다 호숙기가 가장 컸으며, 수확시기에 따른 수분 함량은 1차 수확할 때 가장 높았고 호숙기에 수확할 때 가장 낮은 함량을 보였다. 2. 보리의 건물수량은 10 a 당 1,343 kg였으며 보리와 하계 작물를 작부체계에 따른 건물수량은 수수의 경우 1차 및 2차 수확보다 호숙기에 수확할 때 10,018 kg으로 가장 많았으며, 기장과 피 역시 출수기와 재생 후 수확 시 보다 호숙기에 수확할 때 건물수량이 더 많았다. 3. ADF 함량은 수수는 1차 및 2차 수확 시 보다 호숙기 때가 낮았지만 기장과 피는 호숙기가 더 높은 ADF 함량을 보였다. NDF 함량은 3작물 모두 1차 및 2차 수확 시 보다 호숙기에 더 많은 함량을 보였으며, 조단백질 함량은 1차 및 2차 수확할 때가 호숙기에 수확할 때보다 함량이 더 높았다. 4. 건물 수량에 대한 조단백질 총생산량은 수수의 경우 1차 및 2차 수확할 때보다 호숙기에 수확할 때 약 761 kg으로 가장 많았으며, 기장과 피는 출수기와 재생 후 수확 할 때가 호숙기 보다 상대적으로 높은 함량을 보였다. 5. 가소화양분총량은 3작물 모두 수확시기에 따른 함량 차이는 보이지 않았다.
        4,000원
        53.
        2018.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The objective of this study was to investigate the suitable method for rapid establishment of grassland according to forage species, mixed pastures and installation of mesh at 35 degree angle of cutting area in the middle region of Korea. In agronomic characteristics after wintering, vegetation coverage of Tall fescue(TF) was 74% in monoculture, which was the highest among 3 forage crops. Meanwhile average vegetation coverages of monoculture and mixed pasture were 67 and 92% in treated of mesh, which were 4 and 18% higher than untreated of mesh, respectively. In botanical composition, TF of monoculture and Orchardgrass(OG) and TF oriented mixed were indicated over 94% forage coverage. Meanwhile forage coverages Kentucky bluegrass(KBG) and Red top(RT) of monoculture and Perennial ryegrass(PRG) oriented mixture were 89, 81 and 92% in treated of mesh, which were 7, 6 and 5% higher than untreated of mesh, respectively. In forage productivity, dry matter yield(DMY) of TF(12,537kg/ha) and KBG(11,897kg/ha) of monoculture were significant(p<0.05) higher than RT(9,604kg/ha). Meanwhile DMY of OG(12,227kg/ha), TF(12,823kg/ha) and PRG(11,871kg/ha) oriented mixed were not significant difference(p>0.05). In forage quality of monoculture, in the first year, crude protein of KBG was 13.6%, which was the highest among 3 forage species. Also neutral detergent fiber(NDF) of TF was 56.5%, which was the lowest among 3 forage species. In mixed pasture, in the second year, NDF and acid detergent fiber of PRG oriented mixed were 56.5 and 34.3%, respectively, which was the lowest among 3 mixed pasture. In conclusion, forage species TF was more suitable on initial rootage and continuous forage coverage, OG and TF oriented mixed were more suitable on continuous forage coverage. Also the installation of mesh showed positive effects on initial rootage and maintain forage ratio.
        4,500원
        54.
        2018.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to explore the effects of seeding rate of a seed mixture on grassland productivity and botanical composition. Seeding rates were composed of four different treatments varying by the amount of seed: T1, 50% decrease in seeding rate from standard; T2, standard seeding rate; T3, 50% increase in seeding rate from standard; and T4, 100% increase in seeding rate from standard. In 2016, seasonal changes in grass botanical composition revealed T2, T3, and T4 in portion of grass ratio were the highest with a range of 87–100%, whereas T1 was the lowest of all treatments. In 2017, the botanical composition in T1 showed that the grass ratio in of the first cutting was 91%, but in the fourth cutting its ratio decreased by 75%. The results from both years were combined for each treatment, T4 (11,435 kg ha-1) and T3 (11,162 kg ha-1) demonstrated the highest dry matter yield of the treatments (T1: 8,196 kg ha-1; T2: 9,521 kg ha-1) (p<0.05). As a result, a 50–100% increase in the seeding rate from the standard demonstrated the best grassland yield and botanical composition.
        4,000원
        55.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to investigate the effect of addition of lactic acid bacteria inoculants on quality of rye silage harvested at early heading stage. The nutritive values in lactic acid bacteria (LAB) inoculated group showed similar results to control. The pH of rye silage in LAB inoculation significantly decreased as compared to control (P<0.05). In addition, the content of lactic acid in LAB inoculation significantly increased (P<0.05), but the content of acetic acid in LAB treatments decreased. In addition, lactic acid bacterial counts in LAB inoculation significantly increased as compared to control (P<0.05). Therefore, we suggest that rye silage could be improved by LAB inoculation.
        4,000원
        56.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The present study was carried out to explore the potential effect of shading degrees on yields and nutritive values of forage in forest-grassland. This experiment was conducted this study under different natural shading at National Institute of Animal Science, Cheonan province in Korea, for 2 years (from 2015 to 2016). This experiment was consisted of four different shading degrees, such as full sunlight (control, 10% below), 25% of shading, 35% of shading, 50% of shading. Pasture species used in this study were orchardgrass ‘Kodiwin’, perenial ryegrass ‘Linn’, tall fescue ‘Purumi’, kentuky bluegrass ‘Kenblue’, and white clover ‘Ladino’. Botanical composition of orchardgrass was higher than that of perenial ryegrass, tall fescue and kentuky bluegrass. Dry matter (DM) yields of forage decreased as increasing shading degrees. DM yields of forage significantly decreased as increasing shading degrees and lots of cutting times under increasing shading degrees decreased DM yields of forage. The content of crude protein increased as increasing shading degrees and the contents of acid detergent fiber (ADF), neutral detergent fiber (NDF), the activity of total digestible nutrient (TDN) and in-vitro digestibility (IVD), and relative feed value (RFV) were similar in control and different shading. This study suggests that orchardgrass is major component for forest-grassland and establishment of orchardgrass can be improved by increasing shading degrees.
        4,000원
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