• 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.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 춘계학술대회 논문집
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• pp.21-26
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• 2004

This research presents a modeling and a manufacturing method of insert type milling cutters such as face cutter, flat endmill and ball endmill. The methods introduced in this paper adopts the multi-tasking 5-axis machining that is increasing machining accuracy of holder and position accuracy of bolting points. So this can be used in the basic document of the total package program that involves modeling and manufacturing module in various insert cutters.

• Journal of Biosystems Engineering
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• 제42권2호
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• pp.112-116
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• 2017

Purpose: The purpose of this study was to analyze the milling characteristics of white rice depending on the guide angles of the cutting roller's induced guide, as well as to verify optimum milling conditions for the cutting-type milling machine. Methods: Brown rice, which was produced in Cheongju-si, Chungcheongbuk-do, Republic of Korea, in 2014, was used as the experimental material. The milling characteristics of white rice were measured under six different guide angle levels of the cutting roller, which were none, $0^{\circ}$, $5^{\circ}$, $10^{\circ}$, $15^{\circ}$, and $20^{\circ}$. The quantity of brown rice for each experiment was 500 kg, and the milling characteristics were measured according to the whiteness, rice temperature, cracked rice ratio, broken rice ratio, and energy consumption. Results: The whiteness of white rice maintained a uniform level, indicating at range of $38{\pm}0.5$, regardless of the cutting roller guide angles under all conditions. The rice temperature rise during milling was found to be rather low, at $13.9^{\circ}C$ and $13.6^{\circ}C$ at $10^{\circ}$ and $15^{\circ}$ guide angles, respectively. The cracked rice ratio after milling was 18.67%-19.47%, and the broken rice ratio was 0.68% at a $10^{\circ}$ guide angle, which is the lowest in comparison to other guide angles. Energy consumption was lower when the guide was used compared to that with-out the use of the guide. The energy consumption tended to increase as the cutting roller guide angle increased. Conclusions: From the above results, we conclude that the cutting roller guide angles of $0^{\circ}$ and $10^{\circ}$ are suitable for producing high quality rice during milling with a cutting-type milling machine.

• 한국정밀공학회지
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• 제22권4호
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• pp.167-172
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• 2005

In this paper. micro electrochemical machining (ECM) for micro structure fabrications is presented. By applying ultra short pulses. the chemical reaction can be restricted only to the region very close to the electrode. Micro ECM is applied to machining micro structures through electrochemical milling process becasuse it doesn't suffer from tool wear. Using this method. 3D micro structures were machined on stainless steel. It was found that micro machining is possible with good surface quality in the low concentration electrolyte,0.1 M H₂SO₄. In ECM, as the machining depth increases, better flushing of electrolyte is required for sufficient ion supply. Layer-by-layer milling is advantageous in flushing. However, layer-by-layer milling causes taper of structures. To reduce the taper, application of a disk-type electrode was introduced. By electrochemical milling, various 3D micro structures including a hemisphere with 60 ㎛ diameter were fabricated.

• 한국수소및신에너지학회논문집
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• 제8권4호
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• pp.181-185
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• 1997

The electrochemical properties of the $AB_2$-type (Zr-Ti-V-Ni-Cr-Co-Mn) metal hydride electrodes prepared by ball milling with $AB_5-type\{(LM)Ni_{3.6}Al_{0.4}Co_{0.7}Mn_{0.3}\}$(LM : Lanthanum-rich mischmetal) alloy powder as a surface activator were investigated. By ball milling with $AB_5$ type alloy powder, the activation of $AB_2$ type metal hydride electrode was accelerated resulting in an increase of discharge capacity from 35% to 85% of the maximum capacity at the first cycle. As the amount of surface activator increased the activation rate increased, whereas the discharge capacity increased with 10wt% and decreased with 20wt% addition of the surface activator. When the amount of the surface activator was kept constant as 10wt%, the discharge capacity and the activation rate increased with ball milling time up to 20 hours. However beyond 20 hours of ball milling time, they decreased drastically due to the nano-crystallization or amorphorzation of the alloy powder.

• 산업식품공학
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• 제21권2호
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• pp.110-115
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• 2017

본 연구에서는 절삭식 정미기의 절삭롤러에 장착된 통풍간극링의 통풍구 수와 정백 중 발생하는 미강제거에 필요한 흡인 송풍속도가 정백특성에 미치는 영향을 구명하여 절삭식 정미기 개발의 기초자료를 제시하고자 하였다. 그 결과를 요약하면 다음과 같다. 백도는 모든 조건에서 $38{\pm}0.5$로 측정되어 균일하게 정백된 것으로 나타났다. 정백 후 곡온 상승은 송풍속도가 증가할수록 곡온 상승이 낮아지는 경향을 보였고, 절삭롤러 통풍구 수 3구, 송풍속도 35, 40 m/s 조건에서 각각 $15.4^{\circ}C$ $14.6^{\circ}C$로 나타났다. 동할미율은 절삭롤러 통풍구 수 3구, 송풍속도 35 m/s 조건에서 2.13%로 가장 낮게 측정되었다. 싸라기율은 모든 조건에서 0.762-0.869%로 낮은 범위를 보였다. 백미 1 ton을 생산하기 위한 에너지 소비량은 송풍속도가 증가할수록 감소하는 것으로 나타났다. 따라서 절삭식 정미기의 절삭롤러 통풍구 수와 미강제거를 위한 흡인 송풍속도에 따른 적정 정백조건은 곡온, 동할미율, 싸라기율의 품질적인 측면과 에너지 소비량 등을 고려할 경우 절삭롤러 통풍구 수 3구, 송풍속도 35 m/s 조건이 적절한 것으로 판단된다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 춘계학술대회 논문집
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• pp.394-397
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• 2004

This paper presents a simple analytic method using 2D simulation program for predications of cutting force and machining temperature in dry type milling process. And also, comparison of cutting force and machining temperature obtained from experiment and simulation work is accomplished to distinguish of suitability.

• 대한기계학회논문집A
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• 제28권2호
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• pp.196-205
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• 2004

The cutting characteristics and the deformed layer of nitrogen(N)-added type 316LN stainless steel were comparatively investigated to type 316L stainless steel. The cutting force, the surface roughness(Ra) and the tool wear in face milling works were measured with cutting conditions, and the deformed layers were obtained from micro-hardness testing method. The cutting resistance of type 316LN was similar to type 316L in spite of its high strength. The surface roughness of type 316LN was superior to type 316L for all the cutting conditions. In particular, in the high cutting speed above 345m/min, the surface roughness of the two stainless steels was closely same. The deformed layer thickness of the two stainless steels was generated in the 150$\mu\textrm{m}$-300$\mu\textrm{m}$ ranges, and its value of type 316LN was lower than that of type 316L. This is due to the high strength properties by nitrogen effect. It was found that type 316LN was higher in the tool wear than that type 316L, and flank wear was dominant to crater wear. In face milling works of type 316LN steel, tool wear is regarded as a important problem.

• 한국자기학회지
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• 제24권1호
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• pp.1-10
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• 2014

$Co_2Z$-type hexaferrite 시편을 다양한 합성법을 이용하여 제조하였다. 수열합성법을 이용하여 M-type, $Co_2Y$-type, $Co_2Z$-type을 제조하였으며, 제조된 M-type과 $Co_2Y$-type을 출발물질로 하여 고상반응법(ball milling)과 수열합성법(hydrothermal)으로 $Co_2Z$-type을 제조하였다. 제조된 시편의 결정구조와 미세구조 자기적 성질은 XRD, FESEM, VSM, impedance analyzer를 이용하여 조사하였다. M-type과 $Co_2Y$-type은 단일상의 결정구조를 얻을 수 있었다. 여러 합성법 중에 M+Y ball milling, M+Y hydrothermal에서 제조한 시편이 $Co_2Z$-type hexaferrite의 단일상과 대체로 일치하는 것을 알 수 있었으며, $Co_2Z$-type의 모든 시편들은 이론적인 포화 자화값(50 emu/g)과 비슷한 값을 나타내었다. 소결한 시편들의 투자율은 시약을 precusor로 하여 제조한 $Co_2Z$-type의 투자율이 가장 높았으며, 열처리 온도가 증가함에 따라 투자율은 낮아졌다. 다른 합성법에서는 열처리 온도에 따른 변화가 거의 나타나지 않는 것을 확인할 수 있었다.

• 한국재료학회지
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• 제24권11호
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• pp.591-598
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• 2014

In this research, magnesium powder was prepared by gas atomizing. Refinement behaviors of magnesium powder produced under different conditions were investigated using a mechanical milling (attrition milling) process. Analyses were performed to assess the characterization and comparison of milled powder with different steel ball sizes and milling times. The powders were analyzed by field emission scanning electron microscope, apparent density and powder fluidity. The particle morphology of the Mg powders changed from spherical particles of feed metals to irregular oval particles, then plate type particles, with an increasing milling time. Because of the HCP structure, deformation occurs due to the existence of the easily breakable C-axis perpendicular to the base, which results in producing plate-type powders. An increase in ball size and the impact energy of the magnesium powder maximizes the effect of refinement. Furthermore, it is possible to improve the apparent density and fluidity according to the smoothness of the surface of the initial powder.