• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.581-584
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• 2003

The austenitic STS 304 stainless steel was turned to clarify the effects of tool geometry on the tool wear. The wear of TiN-TiCN-TiC-TiAlN coated tungsten carbide tool was the smallest, exhibiting larger wear in the order of Si-Al-O-N ceramic, TiN coated tungsten carbide, TiN-TiCN-TiN coated tungsten carbide, TiC-TiN cermet and M20 tungsten carbide tools at the same cutting conditions. The S-type tool of M20 with large approach angle showed the longest tool life of all tools used in this tests due to preventing the groove wear of the side cutting edge. The wear of the S-type tool with the rake angle of 15$^{\circ}$became smaller than with that of -5$^{\circ}$, but the tool with the nose radius of 0.8mm did not perform much better with increasing the rake angle.

• 한국발생생물학회지:발생과생식
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• 제1권2호
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• pp.181-187
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• 1997

This study has been conducted to investigate the mating behavior, time sequence of mating and time limit with which female can fulfill spawning and brooding after pre-spawning molting in the giant fresh-water prawn, macrobrachium rosenbergii reared in the laboratory. the results obtained were summarized as follows. Mating happened spontaneously as the following sequences: courting gesture, seizure of female by male, mounting, turning of female, copulation. The entire mating lated approximately seven minutes. The endopodite of 2nd pleopod of male bore the appendix masculins whcih are male's secondary sex characteristic. cinciulli was formed at the distal portion of appendix interna which are on the upper portion of appendix masculins and helped stabilizing the connection of each side of 2nd pleopod during mating. After the connection of each side of 2nd plepod was fixed on the posterior portion of the thoracic sternum in female, a gelatinous spermatophore that emitted at the basipodite of 5th pereiopod during courting gesture was deposited on the ventral groove of 2nd, 3rd, 4th and 5th pereiopod. time limit which female can fulfill copulation and brooding was from 3 hours to 15 hours after pre-spawning molting.

• Journal of Korean Neurosurgical Society
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• 제53권5호
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• pp.288-292
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• 2013

Objective : Vertebral distraction is routinely performed during anterior cervical discectomy and fusion (ACDF). Overdistraction can injure the facet joints and may cause postoperative neck pain consequently. The purpose of this study was to investigate the clinical relevance of distraction force during ACDF. Methods : This study included 24 consecutive patients with single level cervical disc disease undergoing single level ACDF. We measure the maximum torque just before the the arm of the Caspar retractor was suspended by the rachet mechanism by turning the lever on the movable arm using a torque meter. In order to turn the lever using the torque driver, we made a linear groove on the top of the lever. We compared the neck disability index (NDI) and visual analogue scale (VAS) scores between the high torque group (distraction force>6 $kgf{\cdot}cm$) and the low torque group (distraction force${\leq}6kgf{\cdot}cm$) at routine postoperative intervals of 1, 3, 5 days and 1, 3, 6 months. Results : The VAS scores for posterior neck pain had a linear correlation with torque at postoperative 1st and 3rd days ($y=0.99{\times}-1.1$, $r^2=0.82$; $y=0.77{\times}-0.63$, $r^2=0.73$, respectively). VAS scores for posterior neck pain were lower in the low torque group than in the high torque group on both 1 and 3 days postoperatively ($3.1{\pm}1.3$, $2.6{\pm}1.0$ compared with $6.0{\pm}0.6$, $4.9{\pm}0.8$, p<0.01). However, the difference in NDI scores was not statistically significant in all postoperative periods. Conclusion : Vertebral distraction may cause posterior neck pain in the immediate postoperative days. We recommend not to distract the intervertebral disc space excessively with a force of more than 6.0 $kgf{\cdot}cm$.

• 대한기계학회논문집A
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• 제36권10호
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• pp.1189-1193
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• 2012

본 연구는 초소형 광학 시스템을 구현할 수 있는 설계 및 제작의 방법론을 제시하고자 한다. 초소형 광학계에서는 조명 및 결상 광학소자의 성능과 소형화가 조광면의 균질도와 결상 된 이미지의 선명도에 중요한 영향을 미치게 된다. 본 연구에서는 얇은 두께로 실효 광도를 배가시키기 위한 초박형의 LED 빔조형 렌즈를 설계 제작하였다. 상기 렌즈는 중앙부의 비구면렌즈와 외각의 전반사 프레넬 가장자리 부로 구성되어 있다. 설계된 LED 빔조형 렌즈(직경 4.7 mm, 두께 0.6 mm)는 다이아몬드 선삭으로 중앙 비구면부의 전반사(TIR) 가장자리가 정밀하게 가공되었으며, LED 의 빔각을 150 도에서 17.5 도로 축소 시켰다. 다른 광학소자들 마이크로 프리즘, 결상광학용 프레넬 렌즈, 광가이드는 다양한 마이크로 나노 크기의 제조공정으로 일체형으로 성형되었다. 시작품으로 제작된 초소형 광학계($6.8{\times}2.2{\times}2.5mm$)는 마이크로 패턴을 결상의 가능성을 보여주었고, 지문인식용 초소형광학계로서의 성능을 검증하였다.