• 멤브레인
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• 제18권2호
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• pp.168-175
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• 2008

본 연구에서는 평판 지지층 위에 부착된 플라스틱 돌기에 의하여 형성되는 와류가 투과성능에 미치는 영향을 측정하기 위하여 돌기 있는 모듈과 돌기 없는 모듈에서 각각 투과 실험하였다. 운전압력을 0.4 bar에서 1.6 bar까지 증가시키면서 카올린 용액을 투과시킬 경우, 돌기형 평막 모듈은 돌기가 없는 모듈과 비교하여 초기 투과유속 감소 시간이 2배 이상 연장되었고 순수 대비 투과유속의 감소비 역시 1 내지 5% 가량 낮게 나타났다. 레이놀즈수가 1,750인 층류영역에서 돌기에 의한 투과유속 향상은 전이영역에 비하여 약 2배 높게 나타났다. 전반적으로 평막 모듈에 부착된 돌기는 60분 후 투과유속 향상에는 크게 기여하지 못하였지만, 투과실험 초기에는 막오염 방지에 효과적인 것으로 확인되었다.

• 한국전산유체공학회지
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• 제20권4호
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• pp.109-115
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• 2015

In this study, the Stokes flow in the microchannel is analysed where the semicircular protuberances with constant spacing are attached on the upper and lower walls with staggered arrangement. For the low Reynolds number flow in microchannel, Stokes approximation is used and the periodicity and symmetry of the flow are considered to determine the stream function and pressure distribution in the flow field by using the method of least squared error. As results, the streamline patterns and pressure distributions in the flow field are shown for some specific values of the size and spacing of the protuberances, and shear stress distributions on the surface of semicircular protuberances are plotted. Especially, for an important physical property, the average pressure gradient along the microchannel is obtained and compared with that for the case of in-phase arrangement of the upper and lower protuberances. And, for the small clearance between the protuberances of upper and lower walls or between the protuberances and the opposite wall, the average pressure gradient is derived from the lubrication theory and compared with that of the present study.

• 한국응용곤충학회지
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• 제38권3호
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• pp.241-247
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• 1999

본 연구는 느타리버섯 해충인 Coboldia fuscipes (Diptera: Scatopsidae)의 번데기 앞측에 있는 사슴뿔 모양 돌기의 생리적 기능을 구명하고자 수행하였다. C.fuscipes 유충 및 번데기에는 형태적으로 특이한 돌기가 관찰되는데,종령 유충의 몸 두번째 마디에 길이 0.04 mm의 미세돌기 l쌍과 번데기 앞부위에 길이 0.5 mm의 사슴뿔 모양 돌기 l쌍 및 복부에 길이 0.12mm인 6쌍의 강모형 돌기가 관찰되었다.종령 4령 유충의 미세돌기를 제거한 결과,사슴뿔 모양 돌기가 형성되지 않은 번데기가 출현하였으나, 이후 사슴뿔 모양 돌기 유무에 관계없이 정상적인 성충으로 우화하였다.또한, 슴뿔 모양 돌기 존재 여부에 따른 용화시 특성으로는 먹이로 제공된 감자한천 배지 속으로 용체의 함입률에 있어서 현격한 차이가 관찰되었는데,사슴뿔 모양 돌기가 형성되지 않은 번데기는 용체를 바깥으로 노출시키는 경향이 강하였다.그러나,사슴뿔 모양 돌기가 형성되지 않은 번데기의 용화율이나 우화율 등의 생태적 차이는 관찰할 수 없었다. 현미경 관찰 결과, 번데기의 사슴뿔 모양 돌기와 강모형 돌기는 관상의 측면 주세로기관지로 연결되어 기관계를 구성하고 있었다. 이상의 결과플로부터, C.uscipes 먼떼기의 사슴뿔 모양 돌기는 번데기 시기에 중요한 호흡뿔로 작용함을 알 수 있었다.

• 소성∙가공
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• 제12권7호
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• pp.623-630
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• 2003

Nanomachining process, static nanoplowing, is one of the most promising lithographic technologies in terms of the low cost of operation and variety of workable materials. In nanomachining process, chemical effects are more dominant factor compared with those by physical deformation or fracture. For example, during the nanoscratch on a silicon surface in the atmosphere, micro protuberances are formed due to the mechanochemical reaction between diamond tip and the surfaces. On the contrary, in case of chemically stable materials, such as ceramic or glass, surface protuberances are not formed. The purpose of this study is to understand effects of the mechanochemical reaction between tip and surfaces on deformation behaviors of hard-brittle materials. Nanometerscale elasoplastic deformation behavior of single crystal silicon (100) was characterized with micro protuberance phenomena, and compared with that of borosilicate (Pyrex glass 7740). In addition, effects of the silicon protuberances on nanoscratch test results were discussed.

• Journal of Korean Neurosurgical Society
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• 제49권1호
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• pp.49-52
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• 2011

Traumatic intracranial aneurysms are rare, comprising 1% or less of all cerebral aneurysms. The majority of these aneurysms arise at the skull base or in the distal anterior and middle cerebral arteries or their branches following direct mural injury or acceleration-induced shearing force. We present a 50-year-old patient in whom subarachnoid hemorrhage (SAH) was developed as a result of traumatic aneurysm rupture after a closed craniofacial injury. Through careful evaluation of the three-dimensional computed tomography and conventional angiographies, the possible mechanism of the traumatic internal carotid artery trunk aneurysm is correlated with a hit injury by the bony protuberances on the anterior and posterior clinoid processes. This traumatic aneurysm was successfully obliterated with clipping and wrapping technique. The possibility of a traumatic intracranial aneurysm should be considered when patient with SAH demonstrates bony protuberances on the clinoid process as a traumatic aneurysm may result from mechanical injury by the sharp bony edges.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.67-68
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• 2002

The properties and mechanism of silicon protuberance and groove processing by diamond tip sliding using atomic force microscope (AFM) in atmosphere were studied. To control the height of protuberance and the depth of groove, the processed height and depth depended on load and diamond tip radius were evaluated. Nanoprotuberances and grooves were fabricated on a silicon surface by approximately 100-nm-radius diamond tip sliding using an atomic force microscope in atmosphere. To clarify the mechanical and chemical properties of these parts processed, changes in the protuberance and groove profiles due to additional diamond tip sliding and potassium hydroxide (KOH) solution etching were evaluated. Processed protuberances were negligibly removed, and processed grooves were easily removed by additional diamond tip sliding. The KOH solution selectively etched the unprocessed silicon area. while the protuberances, grooves and flat surfaces processed by diamond tip sliding were negligibly etched. Three-dimensional nanofabrication is performed in this study by utilizing these mechanic-chemically processed parts as protective etching mask for KOH solution etching.

• 한국막학회:학술대회논문집
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• 한국막학회 2008년도 춘계 총회 및 학술발표회
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• pp.273-278
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• 2008

• International Journal of Aeronautical and Space Sciences
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• 제11권3호
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• pp.193-200
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• 2010

Through experimental investigations utilizing hypersonic shock tunnel-coaxial thermocouples as well as blow down hypersonic wind tunnel-temperature sensitive paints, the heat flux and the temperature over a protuberance were measured and analyzed. The experimental data were subsequently compared to heat flux data that was obtained by using blow down hypersonic wind tunnel and heat flux gauges. According to the comparison, both sets of data illustrated correlation with one another. The measured heat flux was large when the height of the protuberance was large. Experimental results show that heat flux measurements taken at higher locations were greater than those taken at lower locations. For high protuberances, a severe jump in the heat flux was observed, ranging in values within 0.6-0.7 of the height of the protuberances. However, when the protuberance was sufficiently short, a rise in the heat flux was rarely observed as the protuberance was totally submerged under the separation region.

• Animal Systematics, Evolution and Diversity
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• 제22권1호
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• pp.101-104
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• 2006

Two new species of Arcuphantes Chamberlin and Ivie, 1943 (Linyphiidae), Arcuphantes juwangensis n. sp. and Arcuphantes namhaensis n. sp., are described with illustrations. All Korean Arcuphantes have a convoluted epigynal scape, and show close similarities in their morphological characters, but easily discriminated in the structures of proximal protuberances and the distal wing-shape of their epigynum.

• Tribology and Lubricants
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• 제22권5호
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• pp.237-242
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• 2006

Surfaces found in nature, including biological surfaces have been providing inspiration to modify/fabricate artificial surfaces as solutions for tribological applications. As an example, the concept of 'lotus-effect' has motivated tribologists world wide to modify/fabricate surfaces for enhanced tribological performance. These was done by creating nano/micro-scale asperities on various surfaces using ion beam milling and ion-beam assisted roughening. In order to understand the attributes of natural surfaces, which are inspirational to tribologists, we characterized the surface of two natural surfaces-Nelumbo nucifera (lotus) and Colocasia esculenta leaves. Further, we evaluated their micro-scale friction property, both in their fresh and dried conditions. The characterization of surfaces was conducted using a confocal microscope and SEM, which involved the evaluation of size and distribution of protuberances. The micro-scale friction property was evaluated using a ball-on-flat type micro-tribo tester, under reciprocating motion. A soda lime glass ball (2 mm diameter) was used in these tests. Tests were conducted at the applied normal load of $3000{\mu}N$, at a sliding speed of 1 mm/sec for a scan length of 3 mm. All experiments were conducted at ambient temperature ($24{\pm}1^{\circ}C}$) and relative humidity ($45{\pm}5%$). It was observed that the friction behaviour of the natural surfaces was influenced by their surface characteristics (morphology and distribution of protuberances) and also by the condition (fresh or dried) in which they were tested.