• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 춘계학술대회 논문집
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• pp.223-228
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• 2003

In end milling processes, characterized by use of rotating tools, the underformed chip thickness varies periodically with the phase change of tool. In current study, as a new approach to analyse shear behaviors In the shear plane and chip-tool friction behavior chip-tool contact region during an end milling process. In this approach, an up-end milling process is transformed into an equivalent oblique cutting process. Experimental investigations for two sets of cutting tests i.e.. up-end milling and the equivalent oblique cutting test were performed to verify the presented model.

• 한국산학기술학회논문지
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• 제9권2호
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• pp.311-316
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• 2008

Ag계 분말 삽입금속을 볼 밀링법으로 제조하였다. 밀링공정의 변수들은 밀링시간을 제외하고는 일정하게 하였고 밀링 시간은 24, 48, 72시간들로 정하였다. 밀링에 의해 제조된 삽입금속들은 SEM관찰, DSC분석, 퍼짐성, 젖음성 시험을 통해 평가하였다. 삽입금속들의 브레이징부 특성은 상용금속에 비하여 우수하였다. 48시간 동안 밀링한 삽입금속이 퍼짐성과 젖음 특성이 가장 우수한 조건임을 나타냈다. 또한 브레이징부는 작은 양의 기공을 포함하고 있지만 안정적인 미세조직을 보였고 미세경도는 138VHN으로 나타났다.

• 한국기계가공학회지
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• 제11권4호
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• pp.7-12
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• 2012

The cutting force for peripheral end-milling considering run-out property was estimated and its result was compared with that of measured one. An experimental coefficient modelling was used for the formulation of theoretical end-milling force by considering the specific cutting force coefficient. Also, the specific cutting force, that is the multiplication of specific cutting force coefficient and uncut chip thickness, was used for the prediction of end-milling force. The end-milling force mechanics with run-out was presented for the estimation of theoretical force in peripheral end-milling by considering the geometric shape of the workpiece part. As a result, the estimated end-milling force shows a good consistency with the measured one. And it can be used for the prediction of force history in end-milling with run-out which incurs different start and exit immersion angle in entering and exiting condition.

• 자원리싸이클링
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• 제33권4호
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• pp.22-28
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• 2024

폐 PCB에는 구리를 포함한 다량의 유가 자원이 포함되어 있으며 이를 회수하기 위한 기술 개발이 꾸준히 이루어지고 있다. 일반적으로 폐 PCB를 재활용하기 위해서는 파쇄 및 분쇄와 같은 물리적 전처리가 필요하다. 그러나 물리적 전처리 과정에서 금속의 손실률이 높고 선별도가 낮아 효율적인 재활용 전처리 공정이 필요하다. 본 연구에서는 폐 PCB에서 효율적인 구리 회수를 위해 열처리와 볼 밀링을 동시에 진행하는 고온밀링공정을 적용하였다. 350 ℃에서 밀링 시간과 밀링 속도, 볼의 무게를 변수로 두어 실험을 수행하였으며 볼의 무게 500 g, 밀링 속도 70 RPM, 볼 밀링 시간 5시간 조건에서 90% 이상의 구리 회수율을 보였다. 회수된 구리의 순도는 약 93%이며, 고온 밀링공정 후 회수된 구리를 후공정을 통해 고순도의 구리로 재소재화 가능성을 확인하였다.

• 한국기계가공학회지
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• 제11권4호
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• pp.13-19
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• 2012

There are many dynamic properties in measured end-milling force. So, it is difficult to predict the real static property of end-milling force. Also the behavior of end-milling force is very complex to predict with the measured one. To extract the static property from measured force, it must be filtered and its problem is closely related to a de-noising one. Also this paper presents alternative de-noising method of end-milling force using wavelet filter bank, based on the wavelet transform and its inverse one. In this paper, by comparing the measured force and its wavelet filtered one, the fundamental end-milling force property after wavelet transform is well reviewed and analyzed. This result of wavelet filtering with filter bank shows the static force of end-milling which has severe dynamic properties occurring in entry and exit state of edge emersion into the workpiece.

• 한국분말재료학회지
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• 제9권5호
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• pp.329-335
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• 2002

Recently, the fabrication process of the W-Cu nanocomposite powders has been studied to improve the sinterability through the mechanical alloying and reduction of W and Cu oxide mixtures. In this study. the W-Cu composites were produced by mechanochemical process (MCP) using $WO_3-CuO$ mixtures with two different milling types of low and high energy, respectively. These ball-milled mixtures were reduced in $H_2$ atmosphere. The ball-milled and reduced powders were analyzed through XRD, SEM and TEM. The fine W-Cu powder could be obtained by the high energy ball-milling (HM) compared with the large Cu-cored structure powder by the low energy ball-milling (LM). After the HM for 20h, the W grain size of the reduced W-Cu powder was about 20-30 nm.

• 한국공작기계학회논문집
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• 제13권2호
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• pp.17-24
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• 2004

In end milling process, undeformed chip thickness and cutting forces vary periodically with phase change of the tool. Recently, a model has been proposed to simulate the shear and friction characteristics of an up-end milling process in terms of the equivalent oblique cutting to this. In the current study, a down-end milling process has been replaced with the equivalent oblique cutting process. And shear and tool-chip friction characteristics variation of SM45C steel has been studied using the end-mills of different helix angles. The specific shear and friction energy consumed with helix angle of $50^{\circ}$ is somewhat larger than those of$30^{\circ}$ and $40^{\circ}$. The specific shear energy consumed is about 76-77% of the specific cutting energy regardless the helix angles.

• 한국정밀공학회지
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• 제31권3호
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• pp.269-275
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• 2014

Conventional machining technologies such as a milling process have limitations in accuracy to fabricate microstructures. Deep X-ray lithography using the synchrotron radiation is a promising micromachining process with an excellent accuracy, whereas there are difficulties in the fabrication of multi-layered structures. Therefore, it is mainly used for fabricating simple mono-layered microstructures with a high aspect ratio. In this study, a novel technology for fabricating multi-layered microstructures is proposed by combining two processes. In advance, an X-ray resist material is cut and machined into various shapes and heights by the micro milling process. Subsequent X-ray irradiation process facilitates the fabrication of multi-layered microstructures. The proposed technology can overcome the limitation of the pattern accuracy in conventional milling process and the difficulty of the multi-layered machining in x-ray process. The usefulness of the proposed technology is demonstrated in this study by applying the technique in the realization of various multi-layered microstructures.

• 한국전기전자재료학회논문지
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• 제14권11호
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• pp.904-911
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• 2001

High-density lead zirconate titanate(Pb(Zr$\_$0.53/Ti$\_$0.47/)O$_3$, PZT) ceramics were fabricated by a new milling-precipitation(MP) process improved from the conventional solid state process. This process was progressed by a milling impregnation through mixing ZrO$_2$ and TiO$_2$ powders with lead nitrate(Pb(NO$_3$)$_2$) water solution in zirconia ball media, and then milling precipitation was induced from precipitation of PbC$_2$O$_4$ by adding ammonium of oxalate monohydrate((NH$_4$)$_2$C$_2$O$_4$$.$H$_2$O) as a precipitant. As a result of this process, single-phase perovskite structure was formed at the calcination temperature of 750$\^{C}$ for Pb(Zr$\_$0.53/Ti$\_$0.47/)O$_3$ powders. In addition, the highest density at the sintering temperature of 1100$\^{C}$ was obtained, because of the highly sinterable PZT Powders ground through the re-milling process. Piezoelectric and dielectric properties of sintered sample were improved by MP process.

• 한국기계가공학회지
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• 제9권6호
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• pp.66-70
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• 2010

Using two piezoelectric materials orthogonally arranged, 2-dimensional(2D) vibration in a excitation workpiece table was generated. In this study, micro milling using high frequency 2D vibration was proposed, whose locus of cutting tool is combined with original trochoid locus of milling tool and 2D elliptical locus of excitation table. From the cutting results of 2D vibrational micro milling of nickel alloy, it was observed that the machining quality and the roughness of machined surface were enhanced compared to conventional milling in a side cutting whose immersion ration is relatively low, whereas there was little betterment in a slot cutting.