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PCB 드릴링용 스핀들을 위한 공기 베어링의 최적 설계에 관한 연구
배명일,김형철,김기수 충남대학교 공업교육연구소 2001 論文集 Vol.24 No.1
In this study, the stiffnesses of aerostatic thrust and radial bearings for PCB drilling are analyzed using system of experiment. The results are as follows: the stiffnesses of aerostatic thrust bearing are affected by input air pressure, clearance, number of nozzle. Also, the stiffnesses of aerostatic radial bearing are affected by input air pressure, diameter of nozzle, length of bearing. A recommended design conditions for aerostatic thrust bearing are as follow: input air pressure 7kg_(f)/cm^(2), clearance 0.02mm, diameter of nozzle 0.2mm, number of nozzle 7, bearing inner diameter 26mm and input air pressure 7kg_(f)/cm^(2), clearance 0.015mm, diameter of nozzle 0.2mm, bearing length 45mm, distance of nozzles 10.5mm for aerostatic radial bearing.
기계구조용 탄소강(SM20C)의 단속절삭시 칩의 형상 및공구손상관찰
배명일 한국기계가공학회 2018 한국기계가공학회지 Vol.17 No.2
In interrupted cutting, the workpiece has a groove that impacts both the cutting tool and the workpiece. Therefore, cutting tool damage occurs rapidly. In this study, I performed interrupted cutting of carbon steel formachine structures (SM20C) using an uncoated carbide tool (SNMG120404, P20), and observed tool damage,cutting chip shape, and the workpiece surface. Results: Under the specific cutting conditions of feed rate = 0.066mm/rev, cutting speed = 120 m/min, and depth of cut = 0.1 mm; and feed rate = 0.105 mm/rev, cutting speed= 120 m/min, and depth of cut = 0.2 mm, the observed tool damage was small. Similar chip shape wasobserved (Expt. No. 1, 3, 7). Workpiece damage was observed (Expt. No. 3, 5, 7, 9). Key Words
마이크로 드릴에 의한 구멍 가공시 드릴의 손상과 구멍의 관찰
배명일 한국기계기술학회 2016 한국기계기술학회지 Vol.18 No.4
In this study, i machined micro hole to PCB(Printed circuit board) with ultra precision spindle system for mechanical micro drilling. For this i utilized 0.4∼0.6 ㎜ micro drill and observed cutting edge and hole. Results are as follows; in case of drilling with 0.4∼0.6 ㎜ micro drill, micro hole was made specific range of diameter up to 300 times drilling and micro drilled diameter was bigger than micro drill’s diameter at 300 times over. Error ratio of drilled diameter and damaged hole diameter was within 5 % and 17 %. I observed 0.4 ㎜and 0.6 ㎜micro drill’s cutting edge after 500 times drilling and confirm cutting edge width variation and damage, same result found 1000 times drilling with 0.5 ㎜ micro drill.
A New Speech Waveform Coding Based on the Nonuniform Sampling Method with Separated to High-Low Band
배명진,이주헌,임성빈,이원철,Bae, Myung-Jin,Lee, Joo-Hun,Im, Sung-Bin,Lee, Won-Cheol The Acoustical Society of Korea 1995 韓國音響學會誌 Vol.14 No.5
균일표본화에서 나타나는 샘플간의 잉여정보를 더욱 줄임으로써, 요구되는 데이타량을 크게 줄일 수 있는 방법으로 비균일표본화 방법이 고려된다 그러나, 음성신호의 경우 이러한 비균일표본화 방법을 바로 적용하면, 필요한 데이타량이 균일표본화에 견주어 크게 줄어들지 않게 된다. 특히, 잡음환경하에서는 오히려 균일표본화의 경우보다도 데이타량이 커질 수 있다. 이러한 단점을 보완하기 위해서, 먼저 음성신호를 적당히 저대역 필터링을 한 후 비균일표본화를 적용하고, 고대역성분에서의 오차는 잡음신호로 보완하는 방법을 제안한다. 제안된 방법은 기존의 비균일표본화 방법보다 약1.8배의 데이타압축효과를 얻을 수 있었다. To reduce the redundancy within samples that resulted from uniform sampling method, nonuniform sampling or nonredundant-sample coding methods can be considered. However, it is well known that when conventional nonuniform sampling methods are applied directly to speech signal, the required amount of data is comparable to or mure than that by uniform sampling method like PCM. To overcome this problem, a new nonuniform sampling method is proposed, in which nonuniform sampling is applied to the low-pass filtered speech signal and higher band is compensated by 8 colored Gaussian random noise with various noise levels. By this method, speech signal waveform can be encoded by 1.8 times larger compression ratio than the conventional nonuniform sampling method.
위상 보상된 고조파 스케일링에 의한 음성합성용 피치변경법
배명진,Bae, Myung-Jin 한국음향학회 1994 韓國音響學會誌 Vol.13 No.6
In speech processing, the waveform codings are concerned with simply preserving the waveform of signal through a redundancy reduction process. In the case of speech synthesis, the waveform codings with high quality are mainly used to the synthesis by analysis. Because the parameters of this coding are not classified as both excitation and vocal tract, it is difficult to apply the waveform coding to the synthesis by rule. Thus, in order to apply the waveform coding to synthesis by rule, it is necessary to alter the pitches. In this paper, we proposed a new pitch alteration method that can change the pitch period in waveform coding by dividing the speech signals into the vocal tract and excitation parameters. This method is a time-frequency domain method preserving the phase component of the waveform in time domain and the magnitude component in frequency domain. Thus, it is possible that the waveform coding is carried out the synthesis by rule in speech processing. In case of using the algorithm, we can obtain spectrum distortion with $2.94\%$. That is, the spectrum distortion is decreased more $5.06\%$ than that of the pitch alteration method in time domain. 신호처리에서, 파형부화법은 음성신호의 잉여성분을 감소시킴으로써 파형을 유지하는 부호화 방법이다. 음성 합성의 경우, 고음질의 파형부호화법은 주로 분석에 의한 합성법에 이용된다. 그러나, 파형부호화법은 여기 파라미터와 성도 파라미터로 분리하지 않고 처리하기 때문에 규칙에 의한 합성에 적용되기 어렵다. 따라서 파형부호화법을 규칙에 의한 합성에 이용하기 위해서는 피치변경이 필요하다. 본 논문에서, 우리는 파형부호화법에서 음성신호를 성도 파라미터와 여기 파라미터로 분리함으로써 피치 주기를 바꿀 수 있는 새로운 피치변경법을 제안한다. 이 방법은 시-주파수 혼성영억 방법으로 시간영역에서 파형의 위상성분과 주파수영역에서 파형의 진폭성분을 보존한다. 따라서 파형부호화법은 음성처리에 있어 규칙에 의한 합성을 할 수 있다. 본 논문에서 제안한 알고리즘을 이용한 경우, 단지 $2.94\%의$ 스펙트럼 왜곡만이 일어났다. 즉, 스펙트럼 왜곡이 시간영역에서의 피치변경법보다 $5.06\%$ 이상 감소되었다.