• 한국터널지하공간학회 논문집
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• 제22권4호
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• pp.451-468
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• 2020

단면이 작게 만들어진 노후화된 터널은 만성적인 교통정체를 유발한다. 이는 터널의 확폭을 통하여 해결할 수 있다. 일반적으로 터널을 확폭할 경우, 기계식 또는 발파식 굴착방법을 통하여 기존터널의 외곽부를 굴착하게 된다. 이러한 굴착은 주변 지반뿐만 아니라 기존터널에도 영향을 미치게 된다. Pre-cutting 공법의 적용은 이러한 문제를 효과적으로 해결할 수 있는 방법이 될 수 있다. 따라서 Pre-cutting을 적용하여 확폭을 수행할 경우, 이에 따른 영향분석은 필수적으로 수행되어야 한다. 본 연구에서는 터널 확폭에서 Pre-cutting을 적용할 경우, 이에 따른 영향을 분석하기 위하여 6가지의 지반등급에서 수치해석을 수행하였다. 해석에서는 확대차로와 Pre-cutting의 굴착길이를 변수로 하여 수행하였으며, 기존터널과 확폭터널의 천단침하에 주목하여 분석하였다. 그 결과, 확폭터널의 천단침하는 확폭이 완료가 되면, Pre-cutting의 굴착 길이와 상관 없이 동일한 값으로 수렴하는 것을 확인하였다. 기존터널의 경우, 굴진면의 전방 5 m 내에서 융기가 발생하였으며, Pre-cutting의 굴착 길이가 짧을수록 융기 발생 예방에 효과적인 것으로 나타났다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1996년도 춘계학술대회 논문집
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• pp.41-46
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• 1996

In this study, unsintered and pre-sintered low purity alumina ceramics were machined with various tools to clarify the machinability, optimum tool materials and optimum cutting conditions. The main conclusions obtained were as follows. (1)In the case of dry cutting, the sintered diamond and natural diamond tools exhibit better performance in machining of the ceramic pre-sintered at lower temperature, and the tool lives of both tools in machining the ceramics pre-sintered at high temperature becomes extremely short. (2)The performance of CBN tool becomes better in dry machining of the ceramics pre-sintered at higher temperature. (3)When the pre-sintered ceramics were wet machined with sintered diamond, the tool life becomes considerably long, and higher cutting speed can be used than in the case of the CBN and ceramic tools, the tool lives becomes shorter at wet cutting than at dry cutting, especially exhibiting extremely short tool life in wet cutting with ceramic tool.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.33-38
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• 1995

In this study, unsistered, pre-sintered and sintered low purity alumina ceramics were machined with various tools to clarify the machniability, the optimum tool materials and the optimum tool materials and the optimum cutting conditions. The maon conclusions obtained were as follows. (1) Machined withalloy steel tool, the machinabilty of te pre-sintered ceramics becomes better with the decrease of pre-sintering temperature, but that of unsintered ceramics(white body) was extremely poor. (2) In the case of carbide tool K01, the tool life in machining white body was the longest, and the machinabilty of pre-sintered ceramics becomes poorer with the increase of the pre-sintering temperature. (3) In the case of ceramic tool, the 10000-1100 .deg. C pre-sintered ceramics showed te best machinability within a certain cutting speed range. So far as dry machining, the above combination and conditions showed the highest productivity. (4) When the pre-sintered ceramics were wet machined withsintered diamond tool, the tool life becomes extremelylong, and higher cutting speed can be can be used than in the case offull-sintered ceramics. The productivity of wet cutting is much higher than that ofdry cutting.

• Journal of Biosystems Engineering
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• 제29권5호
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• pp.451-456
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• 2004

To establish a Altari radish pre-processing system far kimchi, the leaves and root tail of the Altari radish cutting de-vices were developed. The cutting resistances depend on the edge angles, oblique angles and cutting speeds were measured and analyzed. The experiments were performed to reveal the optimal conditions that showed the minimum cutting resistances acting on the materials. As the results, the optimum conditions that acting on the leaves were at edge angle $25^{\circ}$, oblique angle $40^{\circ}$ and cutting speed 0.5 m/s, and those acting on the root tails were at edge angle $20^{\circ}$, oblique angle $30^{\circ}$ and cutting speed 0.5 m/s, respectively. Considered a safety conception, the oblique angle of the leaves cutting device was adjusted as $20^{\circ}$, and then the cutting efficiencies of the both devices at these conditions were showed perfect performances.

• 한국기계가공학회지
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• 제11권2호
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• pp.98-104
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• 2012

In this paper, precision processing is carried out for the pre hardened steel(HRC 54), which is one of injection mould materials. Processing characteristics are estimated according to the number of tool cutting blade and roundness is observed by the 3-Dimensional measuring machine. The surface roughness affected by the wire electric discharge machining are measured. Cutting component force of STAVOX is the highest in condition of 2F processing because load per a blade of cutting tool is high. Especially, the difference in Fz is over 20N by cutting load. The slower spindle rotation speed and tool feed rate are, the better cutting component force is. The roundness of hole processed in condition of 4F is good because feed rate is able to be fast. When rotation speed is increased, the surface roughness is decreased. The surface roughness acquired in condition of 2F processing is higher about 50% than 4F processing.

• 생물환경조절학회지
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• 제17권1호
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• pp.60-65
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• 2008

돌나물의 노지 가을삽식을 위하여, 줄기의 삽수 부위(상부, 중부, 하부) 및 삽식 방법(점파, 조파 산파)에 따른 월동전후 생육특성을 조사하였다. 삽수부위에 따른 삽목후 40일째의 월동전 생육은 상부 삽수에서 초장, 근장, 줄기수, 지경수, 지상부 생체중 및 건물중 등에서 유의하게 높았으며, 월동후 개화전(May 10th) 생육은 개체당 줄기수, $m^2$당 지상부 생체중 및 건물중에서 하부 삽수보다 유의한 증가를 보였다. 삽식 방법에 따른 삽목후 40일째의 월동전 생육은 점파($10{\times}10cm$)가 조파나 산파보다 양호하였고, $m^2$당 지상부 생체중 및 건물중도 점파>산파>조파 순으로 높았다. 월동후 생육(May 10th)은 개체당 줄기수, $m^2$당 생체중 및 건물중에서 점파가 조파보다 유의하게 증가하였다. 돌나물의 가을 노지 삽식은 줄기 상부의 삽수를 이용하는 것이 월동 전후 생육 및 수량성에 유리하였으며, 삽식방법은 점파에서의 수량성이 가장 양호하였으나, 생력화를 위해서는 월동후 생체중에서 점파와 유의한 차이를 보이지 않은 혼파방법이 바람직할 것으로 기대되었다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.301-302
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• 2006

Machinability and machining mechanism were examined in the case where resin impregnation treatment was conducted to the Mo-Co hardening particle dispersed iron-based sintered alloy. As a result, the force required for machining decreased significantly compared with the case where resin impregnation treatment was not conducted. This effect is considered to be attributable to the embrittlement of cutting chips produced by the minimization of the cut material deformation.

• Nuclear Engineering and Technology
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• 제54권3호
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• pp.1145-1151
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• 2022

A hybrid cutting using both plasma and end mill was developed for safe and efficient dismantling of nuclear facilities. In this cutting method, a moving arc plasma heats up the workpiece before milling. Thermally softened part of the workpiece is then removed quickly and deeply with an end mill. For the cutting experiments, a three-axis numerical control (NC) milling machine was combined with a commercialized arc plasma torch and used to cut 25 mm thick stainless steel plates. Experimental results revealed that pre-heating by arc plasmas can improve the cutting volume per unit time higher than 40% by reducing the cutting load and increasing the cuttable depth when using an end mill without cutting fluids. These advantages of a hybrid cutting process are expected to contribute to quick and safe segmentations of metal structures with radioactively contaminated inner surfaces.

• 한국기계가공학회지
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• 제16권3호
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• pp.119-124
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• 2017

Machining optimization using typical computer-aided manufacturing (CAM) software mainly depends on tool paths, and it is impossible to predict the behavior of material or cutting force. In this paper, cutting force analysis simulation is performed on the Unibody Case of a mobile phone with the aim of optimizing cutting-force-based machining using the Third Wave Systems' AdventEdge Production Module. Machining time after optimization was shortened by 42% for roughing compared to pre-optimization, and actual machining time was reduced by 36.8%. For finishing, machining time was reduced by 92%, and actual machining time was reduced around 90%. A surface roughness analysis found that the post-optimization surface roughness was $1.16{\mu}m$ Ra, compared to a pre-optimization value of $1.75{\mu}m$ Ra.

• 한국정밀공학회지
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• 제27권9호
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• pp.86-93
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• 2010

Any relative deformation between the cutting tool and the workpiece at the machining point, results directly in form and dimensional errors. The source of relative deformations between the cutting tool and the workpiece at the contact point may be due to thermal, weight, and cutting forces. Thermal and weight deformations can be measured at various positions of the machine tool and stored in the compensation registers of the CNC unit and compensated the errors during machining. However, the cutting force induced errors are difficult to compensate because estimation of cutting forces are difficult. To minimize the error induced by cutting forces, it is important to improve the machining accuracy. This paper presents the pre-calculated method of form error induced by cutting forces. In order to estimate cutting forces, Isakov method is used and the method is verified by comparing with the experimental results. In order to this, a cylindrical-outer-diameter turning experiments are carried out according to cutting conditions.