• 대한환경공학회지
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• 제22권6호
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• pp.1139-1148
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• 2000

산업 폐기물 중 다량으로 발생하는 제강슬래그의 재활용을 위하여 -14/+24mesh 정도 크기의 슬래그를 미분말로 분쇄시 최적 조건을 조사하고 경제적인 분쇄조건을 확립하기 위하여 요구되는 동력을 산출하였다. 이를 위한 분쇄조건으로 ball mill의 회전속도, 분쇄시간, ball의 충진량, 시료의 충진량과 크기 등을 선정하였고 이에 대한 분쇄효율을 산출하였다. 본 연구에서는 임계회전속도의 79% 정도에 해당되는 값이 최적의 회전속도인 것으로 조사되었다. 분쇄시간에 따른 분쇄정도는 일반적으로 시간이 증가함에 따라 증가하는 것으로 나타났지만 분쇄 초기에 비해 분쇄가 더 진행될수록 분쇄효율은 감소하는 것으로 나타났다. Ball의 충진율은 mill내부 용량의 50%인 경우에 최척의 분쇄효율을 보였고, 시료의 충진량과 크기에 따른 입도초사 실험 에서는 시료의 충진량이 적고 원시료의 크기가 작을수록 분쇄정도는 증가하였다. 위의 결과에 의해 Bond의 식을 사용하여 동력효율을 계산한 결과 분쇄시간이 길수록 그리고 회전속도가 최적인 조건에서 동력효율이 가장 크게 나타나고 있음이 관찰되었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.938-942
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• 2002

This paper has studied to obtain the grinding characteristics and optimal grinding renditions of ceramic materials in the grinding with diamond wheel by the experimental plan method. The load on wheel by varying the feed rate was related with the surface roughness due to the minute destruction phenomenon of grains for the Si$_3$${N^4} and Zr{O_2}$. The depth of cut is related with the surface roughness because the grinding is carried out by grain shedding process due to the brittle fracture phenomenon for the ${Al_2}{O_3}$. The major factors affecting the surface roughness and the optimum grinding conditions were obtained with minimum experiments using the experimental plan method.

• 한국재료학회지
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• 제31권5호
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• pp.286-295
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• 2021

This study attempts to find optimal conditions of the friction coefficient using a discrete element method (DEM) simulation with various friction coefficient conditions and three different grinding media with various ball sizes in a traditional ball mill (TBM). Using ball motion of the DEM simulation are obtained using the optimal friction coefficient compared with actual motion; photographs are taken by the digital camera and the snapshot images are analyzed. In the simulation, the rotation speed of the mill, the materials and velocity of the grinding media, and the friction coefficient between the balls and the wall of the pot are fixed as the actual experimental conditions. We observe the velocity according to the friction coefficient from the DEM simulation. The friction coefficient is found to increase with the velocity. Milling experiments using a traditional ball mill with the same experimental conditions as those of the DEM simulation are conducted to verify the simulated results. In addition, particle morphology change of copper powder is investigated and analyzed using scanning electron microscopy (SEM) for the milling experiment.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.561-562
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• 2006

To enhance the precision and productivity of ultra precision aspheric surface micro lens, the development of ultra-precision grinding system and process for the aspheric surface micro lens are described. In the work reported in this paper, an ultra-precision grinding system for manufacturing the aspheric surface micro lens was developed by considering the factors affecting the grinding surface roughness and profile accuracy. This paper deals with mirror grinding of an aspheric surface micro lens by resin bonded diamond wheel and spherical lens of BK7. The optimization of grinding conditions on ground surface roughness and profiles accuracy is investigated using the design of experiments.

• 한국식품과학회지
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• 제34권5호
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• pp.931-934
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• 2002

폐기화 되고 있는 포도씨를 대체 식용유지 자원으로 개발하고자 포도씨에 함유되어 있는 기름의 최적 추출 방법을 확립하고자 실시하였다. Campbell early 포도씨의 일반 성분 분석 결과 압착 법으로 추출한 기름의 수율은 분쇄 후 볶아 증숙한 처리구, 분쇄 후 볶음 처리구, 분쇄 후 증숙 처리구순이었고 볶음 후 분쇄 처리구에서 가장 낮은 수율을 나타내었다. 용매 추출에 의한 수율은 정치 추출하였을 때 ether 처리구가 24시간 77.4%, 48시간 80.9%로 가장 높았고, 그 다음이 methanol과 n-hexane으로 나타났다. 포도씨 기름의 추출수율을 높이기 위한 방법으로 여러 가지 처리를 조합하여 실시한 결과 다음과 같은 순으로 방법이 확립되었다. (1) 수분 $10{\sim}12%$의 포도씨를 $95{\sim}100^{\circ}C$에서 20분 정도 볶음 처리하고 30분간 실온으로 방냉한다. (2) 분쇄기로 1차 $1{\sim}2\;mm$ 정도 입자로 하여 2차 분쇄로 0.5 mm 이하 입자크기로 분쇄한다. (3) 분쇄된 씨를 steam boiler에서 $0.8{\sim}0.9\;kg{\cdot}f/cm^2$의 압력으로 10분 정도 증숙 시킨 후 열 교환 장치가 부착된 압착 추출기에 $6{\sim}\;8kg$ 정도 넣어 추출한다. (4) 이때의 압착력은 $400\;kg/cm^2$에서 $2{\sim}3$분, $550{\sim}600\;kg/cm^2$에서 10분 그리고 $700\;kg/cm^2$에서 기름 흔적이 없어 질 때까지 추출한다. 추출 방법을 달리하여 추출한다. 추출 방법을 달리하여 추출한 포도씨 기름에 대한 관능검사를 실시한 결과, 최적조건으로 추출한 기름이 맛, 향기 및 색깔에서 가장 좋은 것으로 나타났고 그 다음이 분쇄 후 볶아 추출한 기름이 좋게 나타났으며 분쇄 후 볶아 증숙하여 압착한 기름순으로 나타났다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2010년도 춘계학술대회 논문집
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• pp.65-66
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• 2010

To improve the gear noise quality, gear tooth grinding machine are widely used in automotive industry. While using the gear profile grinding machine to improve the gear tooth quality of the transmission, several defects such as chattering, tooth waves that cause the gear noise occasionally happened. But it is very difficult to solve that problem, because there is no one who knows the setting up the optimal grinding condition appropriately. The abnormal manufacturing conditions which make the gear noise make the engineer to spend a lot of time, effort, and money. Due to demands for solving the serious abnormal gear noise happened in the new FF 6th stage automatic transmission in the mass product stage, the vibration checking process in the worm wheel axis, work rotation and fixed axis of the grinding machine were adapted to find the root causes. As a result, gear profile wave are affected by the work rotation axis's unbalance which is caused by worm wheel feeding speed. And a primary and the secondary grinding feeding speed, cutting oil, work fixed forces are also proved as the important factors. After setting up the grinding condition reported in this paper, it was adapted successfully to the grinding machine to manufacture the new FF 6th speed automatic transmissions' output gear. The gear noise was dramatically disappeared and the process and results will offer good guides to the engineers who manufacture the gear with the grinding machine.

• 한국소음진동공학회논문집
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• 제20권7호
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• pp.665-671
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• 2010

To improve the gear noise quality, gear tooth grinding machine are widely used in automotive industry. While using the gear profile grinding machine to improve the gear tooth quality of the transmission, several defects such as chattering, tooth waves that cause the gear noise occasionally happened. But it is very difficult to solve that problem, because there is no one who knows the setting up the optimal grinding condition appropriately. The abnormal manufacturing conditions which make the gear noise make the engineer to spend a lot of time, effort, and money. Due to demands for solving the serious abnormal gear noise happened in the automatic transmission in the mass product stage, the vibration checking process in the worm wheel axis, work rotation and fixed axis of the grinding machine were adapted to find the root causes. As a result, gear profile wave are affected by the work rotation axis's unbalance which is caused by worm wheel feeding speed. And a primary and the secondary grinding feeding speed, cutting oil, work fixed forces are also proved as the important factors. After setting up the grinding condition reported in this paper, it was adapted successfully to the grinding machine to manufacture the new automatic transmissions' gear. The gear noise was dramatically disappeared and the process and the results will offer good guides to the engineers who manufacture the gear with the grinding machine.

• 한국기계가공학회지
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• 제16권5호
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• pp.40-46
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• 2017

A plasma gas control apparatus for semiconductor plasma etching processes securely holds a cathode for forming a plasma, confines the plasma during the plasma etching process, and discharges gas after etching. It is a key part of the etching process. With the advancement of semiconductor technology, there is increasing interest in parts for semiconductor manufacturing that directly affect wafers. Accordingly, in order to replace the plasma gas control device with a CVD-SiC material superior in mechanical properties to existing SiCs (Sintered-SiC, RB-SiC), a study on the grinding characteristics of CVD-SiC was carried out. It is confirmed that the optimal grinding condition was obtained when the result table feed rate was 2 m/min and the infeed depth was $5{\mu}m$.

• 토지주택연구
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• 제15권1호
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• pp.147-156
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• 2024

본 연구는 시멘트 클링커 제조에 사용되는 탄산염 광물인 석회석(CaCO₃)을 CO₂가 결합되어 있지 않은 탈탄산 원료를 사용하여 제조 공정 중에 발생하는 CO₂를 저감하고자 하는 연구로 다양한 산업부산물 중 폐콘크리트에 부착되어 있는 시멘트페이스트를 이용하고자 하였다. 일반적으로 시멘트용 석회석은 최소한 CaCO₃의 함유량이 80% 이상(CaO, 44% 이상)의 것을 사용해야만 시멘트 클링커의 품질을 확보할 수 있다. 하지만 폐콘크리트 미분말의 CaO 함량은 평균 20% 정도로 시멘트 클링커 원료로 사용하기 위하여 CaO 함량을 35% 이상으로 조성비를 올려줘야 이용이 가능하다. 따라서 폐콘크리트 미분말의 조성 광물 경도차이를 이용하여 경도가 상대적으로 낮은 CaO 형태의 광물을 선택적으로 분쇄하여 분급 및 체가름을 할 경우 CaO 함량을 35% 이상 상승시킬 수 있다. 이에 본 연구에서는 분쇄 공정을 통해 경도가 상대적으로 낮은 CaO를 함유한 광물들을 선택적으로 분쇄하여 효율적으로 CaO와 SiO₂ 외 기타 성분을 분리하는 최적 조건에 대하여 실험적 및 통계적으로 검토·분석하였다. 시멘트 크링커 원료로서 탈탄산된 35% 이상 CaO를 함유한 폐콘크리트 미분말 제조를 위한 최적 분쇄 조건 실험 결과, 분쇄 시간 5분 이내, 피분쇄물 종류 30mm, 피분쇄물양 1.0 이상이 최적 조건인 것을 알 수 있었지만 단일 입도의 분쇄물이 아닌 혼합입도의 분쇄물에 대한 검토가 필요할 것으로 판단된다.

• 한국기계가공학회지
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• 제21권2호
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• pp.123-129
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• 2022

Quartz (SiO2) has high abrasion and heat resistances and excellent chemical and mechanical properties; therefore, it is used in various industries, such as machinery, chemistry, optics, and medicine. Quartz is a high-hardness and brittle material and is classified as the topmost difficult-to-cut material, which is because of the cracking or chipping at the edge during processing. Corner wear, such as cracks and chippings that occur during cutting, is a major cause for the deterioration in the machining quality. Therefore, many researchers are investigating various techniques to process quartz effectively. However, owing to the mechanical properties of quartz, most studies have been conducted on grinding, micromachining, and microdrilling. Few studies have been conducted on quartz processing. The purpose of this study was to analyze the machining characteristics according to the machining factors during the slot machining of quartz using a cubic boron nitride (CBN) tool and to select the optimal machining conditions using the Taguchi method. The machining experiment was performed considering three process variables: the spindle speed, feed rate, and depth of cut. The cutting force and surface roughness were analyzed according to the processing conditions.