• 한국정밀공학회지
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• 제15권9호
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• pp.135-144
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• 1998

High speed machining is a key issue in die and mold manufacturing recently. Even though this technology has great potential of high productivity. tool wear accelerated by high cutting speed to the hardened materials is other barrier. In this research, we attempted to reduce tool wear by considering tool inclination angle between tool and workpiece. The boundary lines describing machined sculptured surfaces were represented by both of cutting envelop condition and the geometric relationship of successive tool paths. Chip cross section, and cutting length could be obtained from the calculated cutting edge and the rotational engagement angle. From the simulation results, machining inclination angle of tool of $15^\circ$ was good enough from the point of tool wear and cutting force, and this value was verified through the cutting experiment of high speed ball end milling.

• 한국작물학회지
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• 제57권3호
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• pp.280-285
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• 2012

본 연구는 국내에서 재배되고 있는 조 품종의 도정수율 증진을 위한 도정방법 및 적정 수확시기를 검토한 결과를 요약하면 다음과 같다. 제현횟수와 도정시간에 따라 제현율과 완전미도정수율의 차이가 인정되었고, 이들의 상호작용에 있어서도 유의성이 인정되었다. 조의 완전미도정수율은 제현횟수를 2회, 도정시간을 1분 30초로 하였을 때 높았다. 출수 후 수확일수에 따른 현곡천립중, 제현율, 현곡의 경도, 도정율과 완전미도정수율의 차이가 인정되었고, 이들 요인간 상호작용에 있어서도 유의적인 상관이 인정되었다. 등숙율과 완전미도정수율 향상을 위해 조생종인 황금조는 출수 후 45일(적산온도 $1,148^{\circ}C$), 중생종인 삼다메와 경관1호는 출수 후 50일(적산온도 $1,150^{\circ}C$), 만생종인 삼다찰은 출수 후 55일(적산온도 $1,168^{\circ}C$)에 수확하는 것이 가장 적당하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1816-1819
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• 2003

As a result of milling operation, we expect to have burr at the outward edge of workpiece. Also, it causes undesirable problems such as deburring cost, low quality of machined surface, and bottleneck in manufacturing process. Though it is impossible to totally remove burr in machining, it is necessary to plan a machining process that minimizes the occurrence of burr. In this paper, a scheme is proposed which identifies the tool path of the milling operation with minimum burr. In the previous research, a Burr Expert System was developed where the feature identification, the cutting condition identification, and the analysis on exit burr formation are the key steps in the program. The Burr Expert System predicts which portion of workpiece would have the exit burr in advance so that we can calculate the burr length of each milling operation. Here, the critical angle determines whether the burr analyzed is an exit burr or not. So the burr minimization scheme becomes to minimize the burr with critical angle. By iterating all the possible tool paths in certain milling operation, we can identify the tool path with minimum burr.

• 한국염색가공학회지
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• 제27권4호
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• pp.245-260
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• 2015

The effect of salt milling process on the crystal size, morphology, and color characteristics of C.I. Pigment Red 57:1 was studied. The primitive morphology and color properties of the pigment after synthesis were studied in the former series work. The size and morphology of primary particles and the second aggregation features should be considered because they are very important to determine pigment quality. We compared the primary morphology of pigment particles before drying with the secondary aggregated morphology of pigment particles after drying and salt milling process. Morphological properties were investigated by particle size analysis, X-ray diffraction, and scanning electron microscopy and color measurement was carried out. Significant reduction in particle size as well as enhanced crystallite size after salt milling process was observed. This result might give a difference in color of the pigment, turning into brighter and more blue-toned red color. It was revealed that synthesis condition affect the morphology and color of the pigment even after milling. Increase in HCl concentration in the synthesis process enhanced crystal size and quality forming bluer-red pigments but an increase in $CaCl_2$ concentration resulted in more amorphous crystals forming darker-red pigments after salt milling.

• 한국전기전자재료학회논문지
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• 제20권12호
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• pp.1039-1043
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• 2007

In this paper, in order to develop low temperature sintering ceramics for multilayer piezoelectric actuator application, PMN-PZN-PZT ceramics were fabricated using $LiCO_3,\;Bi_2O_3$ and CuO as sintering aids. And also, their piezoelectric and dielectric properties were investigated according to the milling time. All the specimens sintered at $930\;^{\circ}C$ showed tetragonal phases without secondary phases. With increasing milling time, piezoelectric and dielectric characteristic of specimens increased up to 60 hours milling time and then decreased due to the agglomeration of fine particle. Accordingly, it seems that 60 hour is optimum milling condition. At the sintering temperature of $930\;^{\circ}C$ and milling time of 60 hour, density, dielectric constant(${\varepsilon}_r$), electromechanical coupling factor (kp), mechanical quality factor (Qm), piezoelectric d constant showed the optimum value of $7.95\;g/m^3$, 1382, 0.546, 1749, 330 pC/N, respectively for multilayer piezoelectric actuator application.

• 한국생산제조학회지
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• 제18권3호
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• pp.261-269
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• 2009

Micro end-milling process is applied to fabricate precision mechanical parts cost-effectively. It is a complex and time-consuming job to select optimal process conditions with high productivity and quality. To improve the productivity and quality of precision mechanical parts, micro end-mill wear and cutting force characteristics should be studied carefully. In this paper, high speed machining experiments are studied to construct the optimum process design as well as the mathematical modeling of tool wear and cutting force related to cutting parameters in micro ball end-milling processes. Cutting force and wear characteristics under various cutting conditions are investigated through the condition monitoring system and the design of experiment. In order to construct the cutting database, mathematical models for the flank wear and cutting force gradient are derived from the response surface method. Optimal milling conditions are extracted from the developed experimental models.

• 한국정밀공학회지
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• 제15권5호
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• pp.100-109
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• 1998

In order to increase productivity through unmanned machining in CNC milling process, in-process tool fracture detection is required. In this paper, a new algorithm for tool fracture detection using cutting load variations was developed. For this purpose, developed were tool condition vector which is dimensionless indicator of cutting load and tool fracture index (TFI) which represents magnitude of tool fracture. Through cutting force simulation, tool fracture index was shown to be independent of tool run-outs and cutting condition variations. Using tool fracture index, the ratio of the tool fracture to feed per tooth could be indentified.

• 한국기계가공학회지
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• 제8권1호
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• pp.31-36
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• 2009

Micro-machining technology has been adopted for shape accuracy of micrometer and sub-micrometer scale, surface roughness of tens nanometer in industries. In micro-machining process the quality of machined surface is derived from machining condition and tooling. This paper investigates AE(acoustic emission) and cutting force signals according to machined surface quality related to machining condition. Machined surface quality was analyzed by the AE and cutting force parameter which reflect surface morphology. The characteristics of signal were extracted for process optimization by monitoring both the tool condition and the machined surface texture in micro end milling process.

• 한국소음진동공학회논문집
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• 제18권11호
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• pp.1097-1104
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• 2008

Working condition is one of the most important factors in precision working. In this study, we optimized the vibration acceleration of working progress direction using RSM(response surface methodology) by table of orthogonal array. RSM was well adapted to make analytic model for minimizing vibration acceleration, created the objective function and saved a great deal of computational time. Therefore, it is expected that the proposed optimization procedure using RSM can be easily utilized to solve the optimization problem of working condition. The experimental results of the surface roughness and vibration acceleration showed the validity of the proposed working condition of side wall end-milling as it can be observed.

• 광물과 암석
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• 제33권4호
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• pp.419-426
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• 2020

비전통 저류층에서 에너지 자원의 회수율을 높이기 위해서는 저류층 내의 미세 공극 형태와 연결도 등을 포함하는 공극 구조 연구가 필수적이다. 본 연구에서는 셰일 저류층 내 나노스케일의 공극 구조 연구에 적합한 조건과 방법을 찾기 위해 집속 이온 빔 시스템(Focused Ion Beam, FIB)과 이온 밀링 시스템(Ion Milling System, IMS)을 이용하여 분석을 진행하였다. 셰일 저류층 내 공극 구조 연구를 위해 리아드 분지에서 획득된 A-068 시추공의 시료를 사용하였다. 각 시료마다 특성이 다르기 때문에 시료 전처리 방법과 조건을 달리하여 최적의 조건을 찾았고 FE-SEM을 이용하여 공극 이미지를 획득하였다. 연구 결과 국소 부위의 공극구조를 관찰하기 위해서는 FIB를 사용하여 시표 표면을 밀링 후 바로 공극 이미지를 얻는 것이 효율적이고 반면에 넓은 면적을 단시간에 밀링하여 여러 공극 구조를 관찰하기 위해서는 IMS를 이용해야 한다는 것을 확인했다. 특히 탄산염 광물 함량이 높고 강도가 큰 암석에 대해서는 FIB보다는 IMS를 활용하여 밀링을 수행해야 공극 구조 관찰이 가능하다는 사실이 밝혀졌다. 본 연구를 통해 셰일 저류층 내 공극 구조 관찰을 위한 방법이 정립되었으며 향후 이를 이용한 셰일 가스 저류층 시료 분석을 통해 공극의 크기나 형태가 셰일가스 회수 증진에 미치는 영향을 밝힐 수 있을 것이다.