• 한국정밀공학회지
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• 제13권1호
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• pp.53-61
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• 1996

A clear understanding of the surface formation mechanism due to cutting is very important to help produce a good quality surface. Much of the roughness along the length of a bar being cut in a lathe can be explained in terms of macroscopic tool shape and feed rate. However, the roughness along the direction of cutting requires a different explanation. The formation of surface roughness is a problem in flow and fracture of materials in the vicinity of the tool edge. On a microscopic scale the cutting edge is rounded because it is impossible to grind a perfectly sharp cutting edge. Even if a perfectly sharp cutting edge were obtained it would soon become dull as a result of rapid breakdown and wear of the cutting edge. A research project is proposed in which in the main object is to model the surface formation mechanism due to cutting. The tool was assumed to be dull, that is, its edge has a finite radius. In order to study the effect of the radius of cutting edge on the surface formation, tools having different cutting edges were used. For orthogonal cutting experiment, cast iron and glass were chosen as brittle materials. Plowing forces acting in the cutting edge were estimated and its effect on the surface roughness was studied by observing the machined surface using optical microscope.

• 한국산림과학회지
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• 제106권1호
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• pp.1-9
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• 2017

산림 벌채 후 형성되는 가장자리 효과의 발생 여부과 회복 과정을 이해하는 것은 생태계 천이와 경관 및 서식지의 공간 영향을 분석하고 이해하는 필수 요소임에도 불구하고, 우리나라에서 관련 주제의 실증 연구는 찾아보기 어렵다. 본 연구는 강원 남부 지역의 소나무림 벌채 후 1, 3, 10, 16년이 경과한 장소에 형성된 벌채지 및 임내 가장자리에서 비생물 및 생물 요인의 변화 양상을 선 (20개) 및 방형구 (340개) 조사법을 병용하여 조사하였다. 벌채 후 초기(3년 이내)는 가장 자리에서 인접 숲 내부 방향으로, 15m 깊이까지 식생 피도, 풍부도, 수관 열림도, 그리고 대기 온도 및 습도가 급격하게 변화하였다. 가장자리 형성 이후, 비생물 요인 및 식물 풍부도의 안정화는 각각 10년 및 16년이 소요되었다. 교목종이 초본식물에 비하여 가장자리 환경에서 더 높은 증가 양상을 나타내었고, 교목종의 높은 증가는 하층식생의 동태에 영향을 주었다. 본 연구 결과를 통해 벌채에 의한 직 간접적인 서식지 변화는 최소 인접 산림의 15 m에서 20 m까지, 그리고 16년 수준까지 지속적으로 영향을 미치는 것으로 나타났다. 본 연구 결과는 경관 및 서식지 패치 평가에 필수적인 가장자리 효과의 깊이에 대한 첫 국내 첫 실증 연구자료로 친환경벌채 기준제시 등 활용성이 높다.

• Asian-Australasian Journal of Animal Sciences
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• 제19권1호
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• pp.31-34
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• 2006

The experiment was conducted to determine the effects of cutting interval and cutting height on the yield and nutrient composition of hedge lucerne (Desmanthus virgatus) when grown on a sandy soil in the Northeast of Thailand. The cutting intervals compared were 30, 40 and 50 days between harvests and the cutting heights 30, 40 and 50 cm above ground level. The experiment was a $3{\times}3$ factorial layout in a randomized complete block design with 4 replications-giving a total of 36 plots each $3{\times}3m^2$. Harvested plant material was weighed, dried and the ground subsamples taken for analyses of crude protein (CP), crude fiber (CF), ash, ether extract (EE) and nitrogen-free extract (NFE). At the last harvest the hedge lucerne samples were separated to determine leaf to stem ratios and then analyzed for nutrient composition in the leaf and stem. Results showed that increasing the cutting interval (i.e. advancing age of maturity) increased dry matter and nutrient yields significantly. In terms of nutrient content, it also increased the crude fiber, ash, ether extract and nitrogen free extract percent in the plant. However, crude protein percent was markedly decreased as the cutting interval increased. Increasing cutting height had no effect on dry matter yield and yields of nutrients, but in terms of nutrient content, it increased crude protein and ash content, but decreased crude fiber content. The percent EE and NFE in the plant was unaffected by cutting height. From the results presented it is clear that cutting a stand of hedge lucerne every 40 to 50 days will achieve greater dry matter and nutrient yields than cutting more frequently, at 30 days. The cutting height at harvest, whether 30, 40 or 50 cm above ground level had no effect on dry matter or nutrient yields of hedge Lucerne. Hedge lucerne therefore offers the Thai poultry farmer a useful alternative protein supplement for poultry diets rather than relying on the more expensive soybean meal. As it can be readily and successfully grown on a range of soil types and climates throughout Thailand, hedge lucerne also offers the Thai farmer a valuable additional source of income.

• 한국잠사곤충학회지
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• 제28권2호
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• pp.9-14
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• 1986

고조삽목의 실용화를 위해, 삽상의 종류, 상토, 삽목시기, 발근촉진제의 효과, 삽목전처리, 삼수채취부위 등을 연구한 결과 다음과 같은 결과를 얻었다. 1. 삽목방법 중 활착률이 가장 높은 구는 사토에서 유합조직을 형성시킨 후 삽목하는 구였으며, 보온못자리구에서는 완전히 고사하여 가장 낮았다. 2. 삽목적기는 3월 26일로 이때에는 수상자, 사토상토를 제외하고 활착률 100%를 보였다. 3. 삽목채취 부위별 활착률은 상<중<하부 순으로 높았으나, 유합조직구에서는 중부에서 70-100%의 높은 활착률을 보였다. 4. 발근촉진제 Rootone-F 포도는 지조상·중부, 그리고 온상 20cm구에서 포도하지 않은 것보다 활착률을 높였으나, 다른 구에서는 뚜렷한 효과가 없었다. 5. 상토의 토성은 활착률에 일정한 경향을 보이지 않는다. 6. 삽목전 처리 중 3월 15일 채취, 빙고에 저장하였다가 삽목하거나, 유합조직의 형성후 삽목하는 경우 타처리에 비해 현저히 활착률이 높았으며, 채취후 방치하였다 삽목하는 전혀 활착되지 않았다.

• 한국정밀공학회지
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• 제14권3호
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• pp.28-34
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• 1997

The side burrs and shape distortion resulting from the micromachining of an array of V-shape microgrooves in fresnel lens mould were experimentally invesigated. The focus of this study is on the influence of depth of cut and prism angle on the burr growing rate. The main experiments were con- ducted on the single prism cutting for the convinient of measuring the burr shape and cutting force. From the observation of the burr shape and burr growing rate, it was found that there exits a critical depth of cut below which the burrs are more or less irregular and weak. But above that critical value, the burrs are re- latively clear and stiff.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.1073-1087
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• 1993

Many investigations have been carried out concerning tillage tool performance, including energy requirement . Since the performance of tillage could also be evaluated through the change of soil , then it is necessary to investigate the soil cutting process and the pattern of soil failure. This study was conducted using indoor soil bin, STILT (Soil Tillage Tool Interaction) system. The result shows that the soil bin experiments could provide the clear understandings about phenomena of soil failure. The movement of sil , the successive failures was clearly visualized. The relations between the horizontal and vertical forces to the linear motion blade, the shear force on the shear plane which devides soil layer into several segments were indicated by the fluctuation/vibration of the recorded resistance and forces. The results show that the horizontal force(Fx) and vertical force (Fz) develope their frequencies as the change of velocity of blade (10, 20, 40 mm/sec) for each cutting angle (35, 45, 60 degrees). Resultant force of Fx and Fz are much influenced by the cutting angle.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.783-791
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• 2000

Increasing demands in productivity are propelling the development of new manufacturing methods like hard machining, high speed cutting (HSC) or machining of difficult to machine materials. In these processes the toois are subjected to very severe mechanical, tribological and thermal loads. They fail prematurely by abrasion, cratering, edge breakage and cold welding. The performance of such tools will be enhanced by better and more wear resistant coatings. The development of these new coatings shows a clear trend towards complex multi-component and multi-layer configurations. TiAIN multilayer coating belongs to these coatings for the new cutting tool generation. This paper tries to explain the benefits of the new coatings. TiAIN multilayer coating offers the following advantages: reduction of manufacturing costs. boost productivity, and lower coolant procurement, conditioning and disposal costs.

• 한국환경생태학회:학술대회논문집
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• 한국환경생태학회 2011년 학술대회 논문집 2호
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• pp.122-126
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• 2010

• Journal of Forest and Environmental Science
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• 제33권2호
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• pp.147-153
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• 2017

The purpose of this study was to examine productivity and cost of tree-length harvesting using cable yarding system in a larch (Larix leptolepis) clear-cutting stand located in Pyeongchang-gun, Gangwon-do. We used tree-length harvesting method using cable yarding system with a tower yarder HAM300. The productivity was $17.6m^3/hr$ for felling, $12.4m^3/hr$ for delimbing, $4.2m^3/hr$ for yarding, and $8.1m^3/hr$ for processing. The total cost of the harvesting system was $48,381won/m^3$, which was majorly composed of yarding operation cost, at $40,169won/m^3$ (79.3%), while felling had the lowest cost at $1,154won/m^3$ (4.1%). Major factors affecting felling and processing productivity was tree volume and the number and thickness of branches for delimbing productivity. In addition, we suggest that training and education for machine operators were critical to improve yarding productivity.

• The Korean Journal of Ecology
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• 제12권4호
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• pp.245-256
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• 1989

Nitrogen cycling was in vestigated in Piuns koraiensis plantations with different ages, 1, 2, 3, 6, 9 and 11 years, which were reforested after clear-cutting. Annual N input by bulk precipitation was 10kg., and output by runoff decreased as the plantation aged, especially in-N. The standing N content of the whole vegetation increased approximately 5 times through 11 years. Understory surpassed P. koraiensis plants in the distribution of standing N content for the initial 9 years, but reversed thereafter. Annual N uptake of P. koraiensis plants increased greatly through 11 years, but that of understory increased somewhat until 9 years and decreased thereafter. The maximum N uptake of the whole vegetation was made in the 9-yr-old plantation. In the 1-yr-old one, 59% of the maximum was already absorbed by understory which mainly consisted to herbs. The recycling coefficient, ratio of annual return to rptake, of the whole vegetation decreased as the plantation aged and the value of understory was greater than that of P koraiensis plants. On the contrary, the N use efficiency, ratio of the net primary production to N uptake, of the whole vegetation increased as the plantation aged and the value of understory was less than that of P. koraiensis plants. Consequently, it is emphasized that understory played an important role in such plantation reforesred after clear-cutting for the initial 9 years.