• 한국정밀공학회지
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• 제15권6호
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• pp.58-63
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• 1998

There are lots of factors that are related to the geometric characteristics of machined surface. Among them, the tool path and milling mode (up cut milling or down cut milling) are the easiest controllable machining conditions. Thus, the first objective of this research is to study the effects of them on the milled surface that is generated by an end milling tool. To get precision parts, not only the machining process but also the measurement of geometric tolerance is important. But, this measurement requires a lot of time, because the infinite surface points must be measured in the ideal case. So, the second objective is to propose a simple flatness measurement method that can be available instead of the 3-D geometric tolerance measurement method, using a scale factor and characterized points. Finally, it is also shown that the possibility of flatness improvement by shifting the consecutive fine cutting tool path as compared with the last rough cutting tool path.

• 반도체디스플레이기술학회지
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• 제16권3호
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• pp.20-24
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• 2017

For process improvement and cutting down on expenses in solar cell industry, it is necessary to improve recycling process of wafer manufacturing. In this research, a study is introduced to develop classifier which is for recycling of abrasive. First of all, recycling process of wafer manufacturing is analyzed. And then, 3 steps of experiments such as oil removal, impurities removal and classification were executed. For the classification of slurry, a classifier is designed and manufactured. From experiments, it is verified that ultra sound vibration and flux are very important factors for classification. By experiencing the recycling processes and making devices, the technique can be initiated industry if needed such as decreasing waste and cutting down on expenses.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.475-478
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• 2004

In this paper, a magnet-type automatic pipe cutting machine that binds itself to the surface of the pipe using magnetic force and executes unmanned cutting process is proposed. During pipe cutting process when the machine moves around the pipe laid vertical to the gravitational field, the gravity acting on the pipe cutting machine widely varies as the position of the machine varies. That is, with same driving force from the driving motor the cutting machine moves faster when it climbs down the surface of the pipe and moves slower when it climbs up to the top of the pipe. To maintain a constant velocity of the pipe cutting machine and improve the cutting quality, the authors adopted a conventional PID controller with a feedforward effort designed based on the encoder measurement of the driving motor. It is, however, impossible for the encoder at the motor to measure the absolute position and consequently the absolute velocity of the cutting machine in the case where the slip between the surface of the pipe and wheel of the cutting machine is not negligible. As an attempt to obtain a better estimation of the absolution angular position/velocity of the machine the authors proposes the use of the MEMS-type accelerometer which can measure static acceleration as well as dynamic acceleration. The estimated angular velocity of the cutting machine using the MEMS-type accelerometer measurement is experimentally obtained and it indicates the significant slipping of the machine during the cutting process.

• 한국정밀공학회지
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• 제19권8호
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• pp.126-133
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• 2002

The cutting thickness of ultra-precision machining is generally very small, only a few micrometer or even down to the order of a few nanometer. In such case, a basic understanding of the mechanism on the micro-machining process is is necessary to produce a high quality surface. When machining at very small depths of cut, metal flow near a rounded tool edge become important. In this paper a finite element analysis is presented to calculate the stagnation point on the tool edge or critical depth of cut below which no cutting occurs. From the simulation, the effects of the cutting speed on the critical depths of cut were calculated and discussed. Also the transition of the stagnation point according to the increase of the depths of cut was observed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1811-1815
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• 2003

Investigated is the relationship between tool deflection and geometrical accuracy in side wall machining. Form error is predicted directly from the tool deflection without surface generation. Developed model can predict the surface form error about three hundred times faster than the previous method. Cutting forces and tool deflection are calculated considering tool geometry, tool setting error, and machine tool stiffness. The characteristics and the difference of generated surface shape in up milling and down milling are discussed. The usefulness of the presented method is verified from a set of experiments under various cutting conditions generally used in die and mold manufacture. This study contributes to real time surface shape estimation and cutting process planning for the improvement of geometrical accuracy.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.901-904
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• 2002

The cutting thickness of ultra-precision machining is generally very small, only a few micrometer or even down to the order of a flew manometer. In such case, a basic understanding of the mechanism on the micro-machining process is necessary to produce a high quality surface. When machining at very small depths of cut, metal flow near a rounded tool edge become important. In this paper a finite element analysis is presented to calculate the stagnation point on the tool edge or critical depth of cut below which no cutting occurs. From the simulation, the effects of the cutting speed on the critical depths of cut were calculated and discussed. Also the transition of the stagnation point according to the increase of the depths of cut was observed.

• 한국잠사곤충학회지
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• 제17권1호
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• pp.27-29
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• 1975

춘잠기에 있어서의 가지뽕의 간벌수확의 효과와 합리적인 간벌방법을 구명하기 위하여 시험한 바 다음과 같은 결과를 얻었다. 1. 춘잠기에 있어서의 가지뽕의 간벌수확은 1주일 정도의 간격으로서는 가는 가지 간벌수확구를 제외하고는 별로 효과가 없다. 2. 가는 가지 간벌구는 표준구와의 사이에 유의차는 없지만 약간 증수가 되는 경향에 있고 특히 소량의 가지뽕이 필요한 4령기에 잔조를 벌채하게 되어 그 수확비율이 현실에 적합하다는 이점이 있다. 3. 굵은 가지를 간벌하는 것은 다른 어떠한 수확법보다 못하다. 수량이 많은 굵은가지를 간벌한 후 1주일 정도로서는 나머지 가는 가지의 발육이 크게 호전하지 못하는 까닭이라고 생각된다.

• 대한기계학회논문집A
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• 제37권10호
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• pp.1269-1278
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• 2013

엔드밀링 공정은 형상창성기구의 특성 상, 절삭면적의 주기적인 변화를 피할 수 없다. 그러므로, 본 연구에서는, 가공 중 절삭날과 공작물 사이의 간섭영역에 해당하는 절삭면적의 모델을 확립하여, 가공면 형상 특성과 절삭면적의 관계를 규명하고자 한다. 대상 가공면은 측벽을 선정하였으며, 형상 특성은 축 방향 진직도를 선택하였다. 절삭면적 및 축방향 진직도에 영향을 미치는 특이점 추정 모델의 타당성은 반경 방향 및 축 방향 절삭깊이를 변화시키며 엔드밀링 가공을 수행하여 검증하였다. 연구 결과, 배분력이 음의 값을 갖지 않는 안정적인 엔드밀링 가공의 경우, 상향절삭은 절삭면적이 증가했다. 일정해지는 영역에서, 하향절삭은 절삭면적이 일정했다 감소하는 영역에서 가공면을 창성하며, 영역이 변화될 때 가공면에 특이점이 발생하는 것이 확인되었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.629-634
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• 2004

When it was a localized torrential downpour last year, a natural-slope fell down above a cut-slope. They were caused that stress was opened by cutting slope, ground water level rose quickly and a ground mass strength fell etc. So volume of ground mass increase because of that reasons, finally the disturbed ground was collapse. Therefore I suggest that safety of a natural-slope is a consideration, when a cut-slope is made by cutting ground.

• 한국생산제조학회지
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• 제20권3호
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• pp.232-238
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• 2011

In the present study, Taguchi method is used to determine the rough region first, followed by RSM technique to determine the exact optimum value during milling on a machining center. A region reducing algorithm is applied to narrow down the region of the Taguchi method for RSM. The result from the Taguchi method is fed to train the artificial neural network (ANN), whose optimum value is used to drive the region reducing algorithm. The proposed algorithm is tested under different cutting condition and results show that the introduced algorithm works well during milling process. It is also shown that theoretically obtained optimal cutting condition is very close to experimentally obtained result.