• 한국자원식물학회지
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• 제8권3호
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• pp.217-222
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• 1995

Experiments were conducted to study the effect of IBA, mineral stone and stem hardness on rooting characteristics in mature Aloe vera plant. The rooting ability in matured Aloe vera was of highly significance when the amount of IBA treatment was increased to 5.000mg/l. The treatment of IBA 5.000mg/l, together with mineral stone(v/w 1.5 times), gave more root number, the length and the dry weight of root were, also, higher in semihard wood cutting than soft wood cutting in matured Aloe vera.

• 한국정밀공학회지
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• 제25권12호
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• pp.47-54
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• 2008

Hard turning process can be defined as a single-point machining process carried out on "hard" materials. The process is intended to replace or limit traditional grinding operations that are expensive, environmentally unfriendly, and inflexible. The purpose of this study is to achieve a systematic understanding of machining characteristics and the effects of machining parameters on cutting force, tool wear shape and chip formation by the outer cutting of a kind of wear resistant tungsten carbide V30. Hard turning experiments were carried out on this alloy using the PCD (Poly Crystalline Diamond), cBN (cubic Boron Nitride) and PcBN (Polycrystalline cubic Boron Nitride) cutting tools. The PcBN and the usual cBN tools were used to be compare with the PCD tool and the dry turning was carried out. The PcBN is attractive as the tool material which replaces the PCD. The tool wear width and cutting force were measured, and the worn tool and chip were observed. The difference of the tool wear mechanism among the three tool materials was investigated.

• 한국정밀공학회지
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• 제34권4호
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• pp.237-241
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• 2017

Cryogenic machining uses liquid nitrogen (LN2) as a coolant. This machining process can reduce the cutting temperature and increase tool life. Titanium alloys have been widely used in the aerospace and automobile industries because of their high strength-to-weight ratio. However, they are difficult to machine because of their poor thermal properties, which reduce tool life. In this study, we applied cryogenic machining to titanium alloys. Orthogonal cutting experiments were performed at a low cutting speed (1.2 - 2.1 m/min) in three cooling conditions: dry, cryogenic, and cryogenic plus heat. Cutting force and friction coefficients were observed to evaluate the machining characteristics for each cooling condition. For the cryogenic condition, cutting force and friction coefficients increased, but decreased for the cryogenic plus heat condition.

• 한국초지조사료학회지
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• 제10권3호
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• pp.152-157
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• 1990

To find out the effect of different patterns of nitrogen and potassium distribution on dry matter yield and botanical composition of temperate pastures, a field experiment was conducted with 6 treatments replicated 3 times in a randomized complete block design. It was lasted from September, 1986 to October, 1989 at the Livestock Experiment Station in Suweon. The results obtained are summarized as follows: 1. In early spring, winter hardiness, growth vigour, cold damage and coverage of grasses with 30% dressing of the total amount of N and K20 fertilizer in spring and at the 4th cutting time respectively were better than those of the other treatments. 2. Average dry matter yield for 3 years with heavy dressing in spring and at the 1st cutting time(l1, 187 kg DM/ha) was much more increased by 9% than that of the equally fertilized treatment(l0,24lkg DM/ha). 3. Changes in the botanical composition showed, in general, the same tendency for all treatments except equal N and K20 distribution. However, grassland vegetation with heavy dressing in spring and at the 1st cutting time was changed into relatively good botanical composition with 76.7% grasses, 22.3% legumes and 1.0% herbs at the end of the experiment. 4. By DM yield and botanical composition treatment 3(40-30-15-0-1570) seemed to be an optimal nitrogen and potassium distribution pattern in a temperate pasture.

• 한국초지조사료학회지
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• 제11권2호
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• pp.84-89
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• 1991

본 시험은 alfalfa파종시 겉뿌림 및 다른 파종방법들이 alfalfa의 생육. 건물수량.조단백질 생산량 및 잡초발생에 미치는 영향을 구명하고자 겉뿌림, 겉뿌림+갈퀴질, 겉뿌림+갈퀴질+쇄압, 경운+산파+쇄압 및 경운+조파+쇄 등 5개 처매구를 두고, 1988년 9월부터 1989년 10월까지 축산시험장 초지시험포에서 수행되였으며, 결과를 요약하면 다음과 같다. 1.경운방법으로 6개월후에 토양산도와 토양의 매화학적 특성은 개선되었다. 2 알팔파의 정착개체수는 갈퀴질이나 쇄압으로 증가하였으며, 겉뿌림보다 경운시 크게 증가 하였다 (P<0.05). 3. 1차 이용시 잡초솔은 갈퀴질이나 쇄압으로 감소하였으며, 겉뿌림보다 경운시 크게 감소하였다. 2차 이용시 잡초솔은 전 시험구에서 현저히 감소하였으나 3차와 4차 이용시 잡초솔은 점차 증가하였다. 4 .알팔파의 건물수량은 갈퀴질이나 쇄압으로 현저히 증가하였으며 겉뿌림보다 경운시 유의적인 증가를 보였고(P<0.05), 경운 산파시 가장 높은 수량을 나타냈다. 5. 2차 이용시 조단백질 생산량은 쇄압으로 증가 하였고, 겉뿌림보다 경운시 크게 증가하였다(p

• 한국기계가공학회지
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• 제13권5호
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• pp.50-56
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• 2014

A technique based on the finite element method (FEM) is used in the simulation of metal cutting process. This offers the advantages of the prediction of the cutting force, the stresses, the temperature, the tool wear, and optimization of the cutting condition, the tool shape and the residual stress of the surface. However, the accuracy and reliability of prediction depend on the flow stress of the workpiece. There are various models which describe the relationship between the flow stress and the strain. The Johnson-Cook model is a well-known material model capable of doing this. Low-alloy steel is developed for a dry storage container for used nuclear fuel. Related to this, a process analysis of the plastic machining capability is necessary. For a plastic processing analysis of machining or forging, there are five parameters that must be input into the Johnson-Cook model in this paper. These are (1) the determination of the strain-hardening modulus and the strain hardening exponent through a room-temperature tensile test, (2) the determination of the thermal softening exponent through a high-temperature tensile test, (3) the determination of the cutting forces through an orthogonal cutting test at various cutting speeds, (4) the determination of the strain-rate hardening modulus comparing the orthogonal cutting test results with FEM results. (5) Finally, to validate the Johnson-Cook material parameters, a comparison of the room-temperature tensile test result with a quasi-static simulation using LS-Dyna is necessary.

• 한국토양비료학회지
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• 제31권1호
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• pp.33-38
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• 1998

본 연구는 환경오염과 생물종의 감소 위기에 있는 독일 남서부의 알고이 ($Allg\ddot{a}u$)지방에서 자연 및 환경보호를 위하여 초지이용을 집약적 초지에서 조방적 초지이용으로 전환시 정책 및 기술적 자료를 제공하기 위하여 수행하였다. 초지의 이용회수를 관행인 6회 예취구와 예취회수를 경감시킨 3회 예취구를 두어 초지생산성, 품질, 생태계에 미치는 영향을 구명하였다. 3회 예취구의 건물수량은 관행의 6회 예취구에 비하여 시험 1년차에 ha당 3 ton, 2년차에 0.9 ton낮았다. 예취회수의 감소는 화본과 - 두과목초의 비율에는 영향을 미치지 않았으나 초종간에는 변화를 초래하여 Dactylis glomerata는 증가되고 Lolium perenne는 감소되었다. 3회 예취구는 관행의 6회 예취구에 비하여 조섬유 함량은 높으나 조단백질, 가소화양분 총량, Net Energy Lactation(NEL)은 낮아졌다. 식물체의 질소함량은 6회 예취구에서 3% 이상이었으나 3회 예취구에서는 이보다 낮았다. 3회 예취구의 질소흡수량은 6회 예취구의 ${\frac{2}{3}}$ 정도이었다. 6회 예취구의 질소흡수량은 시험 1, 2년차에 각각 ha당 409, 443kg으로서 3회 예취구에 비하여 157, 135kg 많았다. 이 지역에서 조방적 초지이용으로 전환 시켰을 경우 초지생산성과 목초의 품질이 단기적으로는 매우 저하 되었으나 중장기적으로 수량감소가 완화되고 식생하고 있는 식물종의 수가 증가될 것으로 판단된다.

• 한국초지조사료학회지
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• 제25권2호
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• pp.137-142
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• 2005

본 실험은 고랭지 산지초지에서 예취횟수와 시비수준이 목초의 식생변화와 건물수량 및 사료성분에 미치는 영향을 검토하기 위하여 3년간 실시하였다. 실험은 표고 600m에서 예취횟수를 2회와 3회, 시비수준을 ha당 질소-인산-칼리 200-200-200kg의 소비구 및 280-200-240kg/ha의 표준시비구로 나누어 실시하였다. 화본과목초의 비율은 2회 예취가 3회 예취보다 높았으며, 클로버 비율은 3회 예취한 소비구에서 $16.3\%$로 가장 높았다. 잡초는 모든 처리구에서 $3.7 {\~} 6.7\%$ 비율로 낮은 결과를 보였다. 평균 건물수량은 예취횟수와 시비수준 처리간에 유의차가 없었으나 3회 예취구에서 표준시비구가 소비구보다 높은 경향으로 나타났다. 3회 예취구가 2회 예취구에 비해 조단백질 함량은 높고 조섬유함량이 낮았다. 시비수준에 따른 사료성분에 차이는 없었다. 이상의 결과를 종합하면 대관령지역의 표고 600m에서 적정 예취회수는 식생구성, 건물수량, 사료성분 및 영양소수량 면에서 3회 예취가, 시비수준은 표준시비구(질소 - 인산-칼리 280-200-240kg/ha)가 적당하다고 사료된다. 그러나 대관령지역과 같이 지역적인 여건(복잡지형, 기후불순 등)이나 축산 농가 개인의 여건(수확기계 미비, 인력 등)이 불리한 경우에는 2회 예취, 소비구(질소-인산-칼리 200-200-200 kg/ha)도 가능하다고 사료된다.

• 한국초지조사료학회지
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• 제14권4호
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• pp.281-287
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• 1994

This experiment was canied out to determine the effects of 3cn1, 6cm, and lOcm of cutting height at harvest on the grass growth, dry matter(DM) yield, and weeds development in reed canarygrass(Phu1uris umndinacea L.) pasttire. The cultivars of reed canarygrass used in this study were Palaton. Veuture and Frontier(contro1). and the grass was harvested four times at soiling stage in 1992. The plant height at first harvest was 84, 96 and 94cm in Palaton, Venture and Frontier, respectively. The average regrowth height was same as 59cm in three cultivars. However, the regrowth height by cutting height was 61 -65cm in 6 and IOcm, and 51 -53cm in 3cm of low cutting height. Annual DM yield was not different in three cultivars of Palaton(l2.58lkg), Venture(l2,752kg), and Frontier (12,243kgIha). The yield at first harvmt wa5 significantly high in 3cm of height, however, the forage yields at second, third and fourth harvest were greatly high in 6cm of stubble height(P<0.05). Total yields by 3, 6 and lOcm of cutting height were 12.306. 14,094 and 11,342kg in Palaton, 12,794, 14,155 and 11,307kg in Venture, and 12,258, 12,940, and 11.535kglhg in Frontier, respectively. The highest yield was achieved in 6cm of stubble heigth(P<0.05). Daily DM production during grass regrowth was not affected by cultivars, and the best regrowth was observed by 6cm of cutting height. Development of weeds was high in 3cm of low stubble height, regradless of cultivars. The contents of crude protein, neutral detergent fiber, acid detergent fiber, and hemicellulose were not affected by cultivar and cutting height. In conclusion, it is suggested that the 6cm of cutting height is the most effective for grass regrowth, forage production, and weed control in reed canarygrass pasture. regradless of cultivm of Palaton, Venture and Frontier.

• 한국초지조사료학회지
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• 제43권1호
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• pp.50-55
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• 2023

본 연구에서는 총체벼 세절과 베일러 내 교반이 곤포 헤일리지의 영양소 함량, 발효특성 및 호기적 안전성에 미치는 영향을 규명하고자 수행하였다. 총체벼 세절은 영양소 함량, 발효특성 및 호기적 안정성에 영향을 미치지 않았다. 하지만, 베일러 내교반 시, 총체벼 곤포 헤일리지의 NDF와 lactate 함량 및 lactat: acetate 비율은 감소하였으나 LAB는 증가하였다. 이상의 결과에서, 베일러 내 교반은 총체벼 곤포 헤일리지의 발효품질 개선에 유리한 것으로 확인되었다.