• 한국초지조사료학회지
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• 제19권1호
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• pp.1-10
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• 1999

목초하고 피해를 최소화할 수 있는 방목개시시 초장(주구 3처리 ; 15, 30, 45cm)과 여름철 혼파된 화본 과목초에 경합력이 낮은 화이트클로바 품종(세구 4처리; Regal, Tahora, Brown, STVR)을 선발하기 위해 제주농업시험장의 사료작물시험포장에서 1994년 9월부터 1996년 10월까지 2년간 시험이 수행되었다. 혼파목초의 건물수량은 전체적으로 평균 예취시 초장 30cm 이상에서 유의적 증수를 보였으나(P<0.05) 2년차에는 유의적 차이가 없었다. 2년째 수확시에만 목초의 건물수량이 Brown 품종구에서 타 품종 보다 통계적으로 고도의 유의적 증가를 보였다.(P<0.01). 2년차에 예취시 초장에 따른 식생구성율에 분명한 차이를 발견치 못하였다. 다만 white clover 품종 처리별로 비교할 때 white clover의 비율은 Regal와 Tahora구에서 보다 Brown과 SRVR 처리구에서 낮아지는 경향이었다. 2년차 마지막 예취시에 잡초비율도 주구나 세구간 효과를 발견치 못하였다. 목초의 ADF와 NDF 함량은 예취 초장 15cm에서 가장 낮았고 인 함량은 15cm에서 가장 높았으며 모두 통계적으로 유의차가 인정되었다(P<0.05). 혼파목초의 K 함량은 30cm 초장에서 가장 낮았으며 (P<0.05) 질소 함량은 예취시 초장과 품종간에 상호작용이 있었으며 통계적으로 고도의 유의차가 있었다(P<0.01). White clover의 품종이 목초의 일반성분 함량에 영향을 주지 못하였다. 결론적으로 방목형일 때 15cm 초장에서 화이트 클로바 SRVR을 이용하는 것이 사료가치도 유지하며 두과와 화본과목초 균형을 유지하는 데 적합하다고 사료된다.

• 한국습지학회지
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• 제7권2호
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• pp.145-158
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• 2005

육지로 격리된 거리에 따른 갈대의 생육과 지상부의 예취가 익년 갈대생장에 미치는 효과를 규명하기 위해 2000년부터 2001년까지 경기도 화성시 주곡면 호곡리에서 갈대 자연군락을 대상으로 초장과 건중량을 조사하였다. 육지와 접한 지역은, 갈대의 평균밀도는 122.67개체/$m^2$, 평균초장은 100.36 cm, 개체당 평균 건중량은 4.241 g, 단위면적당 건중량은 $537.574g/m^2$이었다. 그리고 해양방향에서 육지방향으로 이행함에 따라 개체의 초장 및 건중량, 단위 면적 당 건중량이 현저히 증가하는 경향을 보였다. 한편, 육지와 격리된 지역은 평균밀도는 102.30개/$m^2$, 평균초장은 43.894 cm, 개체당 평균 건중량은 0.779 g, 단위면적당 건중량은 $73.495g/m^2$이었다. 또한 해양방향에서 육지방향으로 이행함에 따른 갈대의 초장과 건중량의 변화는 없었다. 예취한 지역에서 익년의 갈대 생장은 예취하지 않은 지역에 비해 초장과 개체당 건중량은 차이가 없었으나 밀도와 단위 면적당 건중량이 현저히 감소하는 것으로 나타났다.

• 대한기계학회논문집
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• 제18권6호
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• pp.1483-1495
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• 1994

A quantitative analysis of a surface roughness for a precision machining of a sculptured surface in milling process is treated under superposition theory in this paper. The geometrical surface rouhgness is calculated as a function of feed per tooth, path interval, radii of tool and cutting edge, and radii of curvatures of workiece. Through machining experiments in a 3-axis machining center, we confirmed the adequacy of the adequacy of the analysis. While cutter mark is neglegible in ball endmilling, it is significant in flat endmilling. When feed per tooth is very small, flat endmilling gives superior finish to ball endmilling. In flat endmilling, cutting condition and cutter path should be strategically chosen to balance the cutter mark height and cusp height.

• 한국정밀공학회지
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• 제12권3호
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• pp.119-129
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• 1995

In this paper, the inclined endmilling process with a 3-axis machining center using inclined jigs is introduced for the purpose of reducing overall Dies/Molds machining time and improving the machining accuracies. In order to analyze the cutting mechanism of a given endmill more accurately, the unification of the cutting mechanism model of 3-different- kind endmills is carried out by using a nose radius as a parameter. By adding radial runouts as a parameter which influences on surface roughness, the superposition method which defines the effective cusp height superposing the cutter mark height and the conventional cusp height is advanced. And 3-D suface topography predicted in this paper looks like the surface normally observed in practice. Through machining experiments, the adequacy of the superposition method was confirmed.

• 한국작물학회지
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• 제42권4호
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• pp.483-488
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• 1997

Brittle culm 특성을 가지는 벼의 가축 조사요 이용성을 위한 적정 예취시기를 구명하여 조사요로서의 수량 및 영양가를 평가하고자 섬진벼 및 Brittle culm인 KL501 품종을 공시하여 무예취, 출수전 및 출수후 10일로 예취시기를 달리하여 1995년 호남농업시험장 수도포장에서 수행된 결과를 요약하면 다음과 같다. 1. 초장은 품종 및 예취시기간 차이가 인정되었으나 재생초장은 품종에 관계없이 1차 예취시기가 빠를수록 컸으며 분얼경수는 품종 및 예취시기간 차이가 뚜렷하였고 재생경율은 1차 예취시기를 빨리 할수록 높아지는 경향이었다. 2. 조단백질, 조지방 및 NFE 함량은 1차 예취시 예취시기가 빠를수록 많았으나 조섬유, 조회분함량은 반대의 경향이며, 2차 예취시에는 1차 예취시기가 빠를수록 조단백질, 조지방 및 NFE 함량이 적어지며 조섬유, 조회분함량은 많았다. 3. 청예수량은 출수기 예취가 다른 예취시기보다 많았는데 섬진벼는 4.49ton/ha, KL501은 4.75ton/ha이며 건물수량은 섬진벼가 1.12ton/ha, KL501은 1.16ton/ha이었다. 4. TDN 함량은 예취시기가 빠를수록 높았으나 2차 예취시에는 1차 예취시기가 늦을수록 높았고 KL501은 어느 예취시기에서나 섬진벼보다 TDN 함량이 높았으며, TDN 수량은 출수기 예취시 섬진벼는 0.60ton/ha, KL501은 0.62ton/ha으로 다른 예취시기보다 많았다.

• 한국생산제조학회지
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• 제20권5호
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• pp.523-527
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• 2011

Polycarbonate (PC) polymer is an engineering plastic which has large tensile strength and impact resistance and is wildly used as functional parts like micro mold. Direct machining of PC materials produces lots of burrs and rough surface due to large ductility and weak heat resistance and hence it is very difficult to machine PC materials using cutting tool to make micro-parts. In this study, elliptical vibration cutting (EVC) or 2-dimensional vibration cutting was performed to minimize the size of micro V-grooves on PC material. From the experimental results, it was observed that as the cutting depth and pattern size become smaller, the better machining quality was obtained, which is attributed to the positive effect of EVC that is dependent on the ratio of vibration amplitude to cutting depth. As the height of V-groove becomes less than $1.8{\mu}m$, however, the machining quality becomes lower as the pattern size decreases.

• 한국농공학회지
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• 제17권4호
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• pp.3897-3920
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• 1975

Since the most of Korean dairy and cattle raising farms are too small to introduce western mechanized farming, it is necessary to develope small size equipments. This study has been carried to develop a rotary mower as on attachment of 8 to 10 horse powertiller which is widely spread in rural area. It will not ony be helpfull for the farmers to harvesting hay grass but also desirable to increase the power tiller utility. The protto type rotary mower designed through the fundamental investigations, has been modified and improved through the field trials, and a series of field tests has been carried to investigate its performance and economic feasibility comparing with existing vailable harvesting equipments. The results are as follows; 1. To increase the stability, two guide wheels are attached to both side of the protto type rotary mower. 2. To prevent the clinging of tall grasses, the vertical driving shafts are covered with cylindrical protectors. 3. The cutting height is adjustable in 8 steps from 2.5 to 20 centimeters by changing the length of guide wheel legs. 4. The practical Critical cutting speed were always higher than theoretical value in both case of single cutting blade and three when the cutting depth was 25 millimeter. 5. The peripheral speed of cutting blade was varied in response to the change of engine speed, mean while the peripheral speed was adequate as it was changhed from 25 to 35 meter per second when the power tiller is operated in proper working ground speed. 6. The time requirement to harvest 10 a were 88.7, 54.6 and 41.4 minutes for the first, second and third stage of ground speed respectively, and because of the difficulty of delivery, it was observed that operating with fourth stage of ground speed was not recomanendable when the grass height is taller than 90 centimeters. 7. The performance of rotary mower were 1.1-1.7, 1.4-4.0, 3.8-11.8 and 7.4-22.0 times of reciprocating mower, portable disc type cutter, hay scythe and ordinary sickle respectively. 8. When the slope exceeds, 20 degree the downward harvesting operation was impossible because of the excessive front end weight, while less than 5 degree of land slope did not effect in field operation. 9. Increased traveling spee caused higher cutting height and slight cutting failure, but seems not to effect to the gross yield, and the efficiency of cutting width were from 83 to 94 precent. 10. Tn rank of economy were rotary mower (3,2 stage operation), reciprocating mower, hay scythe, portable disc type cutter and sickle in order when the annul operation exdeeds 100 hours. From the above results, it is convinced that the protto type rotary mower is good enough to the livestock farmers as a hay harvesting equipment because of its economy, hardiness in operating and its out standing performance and hopefully it will contribute to the extension of Korean livestock farming.

• Journal of Forest and Environmental Science
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• 제20권1호
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• pp.40-50
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• 2004

이 연구는 강원대학교 학술림내 천연활엽수림을 대상으로 적절한 보육 벌채 시업 방안을 마련하기 위하여 임목의 형질을 평가하고, 형질에 따라 불량한 임목들을 제거하는 벌채 시업 방안을 제시함으로서, 임목형질 평가 방법을 이용한 천연활엽수림의 개선별 시업 적용을 예측하기 위하여 실시되었다. 연구대상 임분의 평균 ha당 본수는 717 본이었으며, 평균직경은 21.1cm, 평균수고는 13.6m로 파악되었다. 상층에는 졸참나무, 굴참나무, 신갈나무, 쪽동백나무, 느릅나무 등의 순으로 우점도가 높은 것으로 나타났다. 4가지의 임목 형질별로 등급을 부여하고, 등급별로 보육 별채를 할 경우마다 단위면적당 임목수, 직경, 수고의 변화를 추정하였다. 형질 등급을 높여서 벌채할수록 임목 본수는 감소하나 임목 형질이 향상되는 효과를 보일 것으로 예상되었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.942-946
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• 1997

In this research,we suggest a virtual machining system that can simulate sutting forces at the stage of design. Cutting forces,here, are modeled form the machanistic model of the ball end milling. To this end, we need undeformed chip thickness which is used for calculating chip load. It is derived form the z-map data of a CAD model. That is, chip load is the height difference between the cutting tool contact point and the workpiece at arbitrary position. The tool contact point is referred from the cutter location. Form the experimental verification, we can simulate machining process effectively to the slot and the side cutting of ball end mill.

• Design & Manufacturing
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• 제17권2호
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• pp.22-26
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• 2023

As Light-Emitting Diodes(LEDs) continue to advance in performance, their application in automotive lamps is increasing. Automotive LEDs utilize light guides not only for aesthetics but also to control light quantity and direction. Light guides employ patterns of a few hundred micrometers(㎛) to regulate the light, and the surface roughness(Ra) of these patterns can reach tens of nanometers(nm). Given that these light guides are produced through injection molding, mold processing technology with high surface quality micro-patterns is required. This study serves as a preliminary investigation into the development of high surface quality micro-pattern processing technology. It examines the surface roughness of the workpiece based on the cutting direction of the pattern and the cutting fluid type when cutting micro-patterns on STAVAX steel using cubic Boron Nitride(cBN) tools. The experiments involved machining a step-shaped micro-pattern with a height of 60 ㎛ and a pitch of 400 ㎛ in a 22×22 mm area under identical cutting conditions, with only the cutting direction and cutting fluid type being varied. The machining results of four cases were compared, encompassing two cases of cutting direction(parallel to the pattern, orthogonal to the pattern) and two cases of cutting fluid type (flood, mist). Consequently, the Ra value was found to be the highest(Ra 128.33 nm) when machining with the flood type in parallel to the pattern, while it was the lowest(Ra 95.22 nm) when machining with the mist type orthogonal to the pattern. These findings confirm that there is a difference of up to 25.8 % in the Ra value depending on the cutting direction and cutting fluid type.