• 한국항공우주학회지
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• 제34권3호
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• pp.51-59
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• 2006

교반기 내에서의 교반속도 변화에 따라 제조된 자가치료용 마이크로캡슐의 물리적 특성을 입도분석기와 광학현미경을 통해 실험적으로 관찰하였다. 또한 자가치료용 마이크로캡슐의 제조공정을 이해하기 위해 3차원 수치해석의 수행을 통해 교반기 내에서의 유동 특성을 조사하였다. 연구결과에 따르면, 교반기 내에서의 교반속도는 마이크로캡슐의 크기를 결정하는 주요 인자임을 확인하였다. 액체가 혼합된 교반기 내에서는 회전하는 임펠러에 의해 제트와 끝단 와류 성분이 발생하였으며 임펠러의 블레이드 주위에 형성되는 와도는 교반속도가 높아질 때 증가함을 알 수 있었다. 또한 자가치료용 마이크로캡슐의 크기는 끝단 와류와 같은 작은 크기의 혼합 패턴 유동에 큰 영향을 받았다.

• 한국항공우주학회지
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• 제33권12호
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• pp.76-82
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• 2005

본 연구에서는 축류형 마이크로터빈의 단 수를 단 단에서부터 최대 6단까지 변경하면서 각 단에서의 공력특성을 측정하였다. 실험에 사용된 마이크로터빈은 터빈입구에서 유량계수가 2.0, 부하계수가 3.25이며 유로의 평균직경이 25.8mm인 소형 축류형 다단터빈이 적용되었다. 정익과 동익의 솔리디티는 0.67~0.75 범위의 값이 적용되었으며 입구에 일정한 질유량과 전압력으로 조정한 후에 터빈의 부하를 변경하면서 탈설계 영역에서의 공력특성을 측정하였다. 본 실험에서는 단 당 최대 2kW/kg/sec의 비출력이 얻어졌으나 단수의 증가에 따라 비출력의 증가폭은 다소 완화되었으며, 토오크의 경우는 단수가 증가되면서 낮은 회전수 영역에서는 토오크의 증가폭이 일정하나 높은 회전수영역에서는 토오크의 증가폭이 둔화되었다. 블레이드의 높이에 비하여 팁간격의 영향이 크므로 터빈의 효율은 낮으나 단 수의 증가에 따라 증가가 가능하다.

• 한국유체기계학회 논문집
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• 제16권1호
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• pp.17-23
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• 2013

Recently so much attention has been focused on renewable energy and, since its sources to exploit are already almost saturated in the country, the practical alternative to this situation could be a micro-turbine which uses the low head and low flow. From a point of view of local micro-turbine design capacity and manufacturing technology, the problems such as the accumulation of technical skills, the expansion of related industries, the national policy expansion and the turbine efficiency to improve are still vulnerable and it's true that there are also negative views about the economic feasibility, the technicity and the operation management of the micro-turbine. However, if the improvement can be done in technology of low-head double regulation micro-turbine to generate more outputs and the operation management can be reliably realized, the micro-turbine will be re-evaluated as an appliable source of renewable energy, even the output is small, and by a paradigm shift, it could realize a power generation as an economic and rational system.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2016년도 추계학술대회 논문집
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• pp.176-176
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• 2016

마이크로 블레이드 제조를 위한 기초 연구로서, 전기도금 방법을 이용하여 Ni 및 다이아몬드 분말을 복합도금을 시켰다. $15{\sim}25{\mu}m$ 크기 분포를 갖는 다이아몬드 분말 농도 변화에 따라 전착되는 다이아몬드 분포 및 전기도금 용액 내 Ni 농도 변화에 따라 전착되는 다이아몬드 분포를 관찰하였다. 이를 위하여 광학현미경, 전자현미경(SEM), EDS 및 XED를 이용하였다. Ni 농도 변화보다는 다이아몬드 분말 농도 변화가 전착되는 다이아몬드 분포에 더 큰 영향을 미침을 알 수 있었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.206.1-206.1
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• 2011

Recently, various developments in the area of small hydropower have being made and small hydro turbines are suitable for domestic use because it is a clean and renewable energy source. A small hydropower generator produces power by using the different water pressure levels in pipe lines and energy which was initially wasted by use of a reducing valve at the end of the pipeline is instead collected by a tubular-type hydro turbine in the generator. In this study, in order to acquire the performance of tubular-type hydro turbine applied, the output power, head, efficiency characteristics due to the different guide vane and runner vane angle are examined in detail. Moreover, influences of pressure and velocity distributions with the variation of guide vane and runner vane angle on turbine performance are investigated by using a commercial CFD code.

• 한국표면공학회지
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• 제41권6호
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• pp.335-340
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• 2008

Cutting performance and wear behavior were studied with the diamond micro-blade of Cu/Sn bond materials containing various amount of lubricant materials such as graphite and $MoS_2$. Measurement of instantaneous electric power consumption for cutting glass workpiece at the constant velocity was conducted and proposed as a method to assess cutting efficiency. The energy consumption of micro-blade for glass cutting decreased with the content of graphite and $MoS_2$ while wear amount of blade in volume increased with the amount of lubricant addition during the dicing test. It is because that hardness, flexural strength, and fracture toughness ($K_{IC}$) reduced with the amount of lubricant addition. Blades with $MoS_2$ additive showed higher mechanical properties than those with graphite additives when the same amount of the lubricant additive in wt.% was added. Due to the lower density of graphite than $MoS_2$, higher volume fraction of graphite could result in stronger effect on lowering electric power consumption by reducing the friction between blade and work piece however increasing wear rate due to the reduction in strength and fracture toughness. Adhesive wearing mode of micro blade could be remarkably improved by the addition of graphite as well as $MoS_2$.

• 대한심미치과학회지
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• 제30권2호
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• pp.91-101
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• 2021

치간유두의 Connective Tissue Graft (CTG)는 좁은 공간 때문에 아주 까다롭다. 그래서 치간유두의 재생은 아주 도전적인 과제라고 생각한다. 이렇게 인접치와의 좁은공간에서 잇몸이식은 아주어렵지만, 3mm의 공간을 만들 수 있다면 CTG는 그렇게 어렵지 않다. 그래서 교정력을 이용하여 임시적으로 3mm의 공간을 만들어 주고 잇몸이식을 진행하였다. CTG는 마이크로블레이드를 이용하여 치은박리를 시행하였고, 치아사이의 공간에 수직절개를 만들어 그곳을 이용해서 결합조직을 이식하였다. 유지기간후에 교정력을 이용해 다시 치아사이의 공간을 모아서 치아를 배열하였다. 이 방법을 통해 치아사이의 치간유두를 재생하였고 이 술식을 이름을 ELSA (Enlargement of space - Labial graft - Squeezing - for Augmentation of papilla)로 이름지었다. 치주질환 등으로 치간유두가 소실된 경우, ELSA technique을은 치간유두를 재생하는 아주 효과적인 방법이다.

• 한국표면공학회지
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• 제45권1호
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• pp.37-42
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• 2012

$WS_2$ powder was added to the Cu/Sn bond metal of diamond micro-blades for machining of semi-conductor and IC chips to improve cutting efficiency. The effect of $WS_2$ additive on cutting efficiency was investigated and compared with the micro-blades with $MoS_2$ developed in previous research. Flexural strength, frictional coefficient, and wear resistance of blades decreased with $WS_2$ but wear depth increased. It was found that the blades including $WS_2$ consumed less momentary energy than the blades containing $MoS_2$ during dicing test. Micro-blades containing $WS_2$ exhibited lower flexural strength than the blades with $MoS_2$ resulting from higher amount of sintering defects relevant to the less effectiveness of $WS_2$ on fluidity. The effect of $WS_2$ and $MoS_2$ on fluidity during sintering was analyzed in terms of mismatching degree between the longitudinal direction of lubricant particles and the perpendicular direction to the compact loading. The blade with 8.1 vol.% of $WS_2$ showed the best cutting efficiency.

• 한국표면공학회지
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• 제43권1호
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• pp.41-45
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• 2010

The effect of $MoS_2$ and graphite content on wear resistance and mechanical properties of Cu/Sn bonded diamond micro blades was comparatively investigated in terms of volume and weight fraction. For the evaluation of endurance and cutting performance, instantaneous electric power consumption and cumulative wear loss during cutting glass work piece at constant velocity were measured with the micro blades of the wide range of lubricant content. The energy consumption of blades for glass cutting decreased with the content of lubricants. Wear amount of blade in volume increased with the amount of lubricant addition. It was found to be relevant to the decrease in flexural strength and hardness with the amount of lubricants. With the same amount of lubricant content in volume fraction $MoS_2$ showed superiority in mechanical properties and cutting performance than graphite while graphite could result in stronger effect on lowering electric consumption during cutting work piece for the same weight percent fraction than $MoS_2$ because of lower density.

• 한국표면공학회지
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• 제46권1호
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• pp.22-28
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• 2013

$WS_2$ particles were added to micro-diamond blades with Cu/Sn binding metal as lubricants to improve cutting efficiency. It was found in previous works that the added $WS_2$ lubricant could reduce remarkably the momentary energy consumption during dicing tests but increased wear rate slightly owing to weak bonding between lubricant particles and bond metals. In the present work, the surface of $WS_2$ lubricant particles were etched for activating the surface of $WS_2$ particles that provide even distribution of particles during powder mixing process and improvement of wetting at the interfaces between $WS_2$ particles and molten Cu/Sn bond metals during pressurized sintering so that could provide the improved strength of micro-blades and result in extended life. Chipping behavior of workpiece with the types of micro-blades including $WS_2$ were compared because it is important in semiconductor and micro-packaging industries to control average roughness and straightness of sliced surface which is closely related with quality.