• 한국정밀공학회지
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• 제29권1호
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• pp.114-120
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• 2012

We present a simple and low-cost method to fabricate poly(methyl-methacrylate) (PMMA) nanochannels with various shapes by combining the standard optical lithography with a PMMA layer transfer and collapse technique. We utilized PMMA membrane reflowing/collapsing phenomena into microchannels to fabricate nanochannels at both corners of arbitrarily-shaped microchannels. This allows nanochannels with various shapes such as curved nanochannels as well as straight nanochannels to be easily fabricated since the shape of the microchannel determines the shape of the nanochannels. This nanochannel fabrication method is simple, flexible, and low-cost since the standard optical lithography with low-resolution optical masks can be used to fabricate nanoscale channels as small as 100 nm wide with various shapes. Also, the sealing of nanochannels can be naturally achieved while the nanochannels are formed through the polymer layer transfer and collapse.

• 한국정밀공학회지
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• 제29권10호
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• pp.1110-1118
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• 2012

In this study, for reducing the residual vibration in high speed motion control stage, an improved 5th order polynomial motion profile was developed. When a stage is moving, the current through the motor coils has the same profile of input motion profile of acceleration, therefore the characteristics of the acceleration input profile directly affect on the performance of the amplifier that includes the current control loop. Commonly low cost amplifier and motor has a narrow current control bandwidth, therefore the proposed algorithm was designed based on this practical constraint. Simulation and experimental results showed that the proposed algorithm clearly has low residual vibration characteristics than conventional 5th order polynomial motion profile on the same drive condition.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송∙미디어공학회 2017년도 하계학술대회
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• pp.207-208
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• 2017

최근 보급되는 스마트 디바이스들은 실외뿐만 아니라 실내의 위치를 측정할 수 있는 기술들을 제공하고 있다. 실외 위치 측위 같은 경우는 기존의 GPS(Global Positioning System)를 사용하는 것이 일반적이지만, 실내 위치 측위는 기존의 GPS 방법으로는 한계가 있어 다양한 새로운 방법들이 연구 중에 있다. 그 중 가장 대표적인 방법은 BLE(Bluetooth Low Energy) 기반의 비콘(beacon)을 활용하는 것이다. 그러나 이 또한 추가적인 하드웨어가 필요할 뿐만 아니라 충전이 필요하다는 단점이 존재한다. 따라서 본 논문은 상기 단점들을 극할 수 있는 OCC(Optical Camera Communication)를 활용한 실내 위치 측위 기술을 고려한다. 특별히 공연장 내에서 관객들이 소지하고 있는 스마트 디바이스 카메라의 상대적인 위치정보를 획득하는 시스템을 제안한다. 이는 추가적인 하드웨어를 필요로 하지 않고 비동기식 접근이 가능하다는 장점이 있다. 본 논문에서 제안한 시스템을 통해 획득된 위치정보들은 촬영한 영상과 함께 저장되어 다양한 시점을 제공하는 응용데이터로 활용될 수 있을 것으로 기대한다.

• 폴리머
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• 제38권4호
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• pp.477-483
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• 2014

Poly(lactic acid) (PLA) and poly(${\varepsilon}$-caprolactone) (PCL) blends with various components for melt-blown non-wovens were prepared by a twin-screw extruder. Tributyl citrate (TBC) was added in order to improve the miscibility between PLA and PCL. The results showed that small circular particles of PCL were dispersed in PLA matrix uniformly. The addition of PCL had the heterogeneous nucleation effect on the crystallization of PLA and decreased thermal stability of PLA. The flow of pure PLA and blends approached to Newtonian liquid at a low shear rate and expressed more obvious viscoelasticity at a high shear rate.

• 한국태양에너지학회 논문집
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• 제32권3호
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• pp.129-137
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• 2012

This thesis introduced an azimuth tracking prismatic daylighting system. The system improved several issues of the previous passive prismatic daylighting system: low efficiency at sunrise and sunset, glare effect and polarized. The system was developed to track the movement of sun with azimuth tracking device, and it has its own power from the attached solar cells. We compared the with previous passive one in terms with system efficiency and daylighting factors(DF).

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.375-380
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• 2008

This study have processed the developing of vane damper with accurate control by using gear which is a flow-control equipment of marine boiler's FD fan on this research. For the developing of vane damper, we have corrected some problem from welding & assembly process by changing the design, and for the case of an emergency case, we have applied the easy disassembly & assembly on that vane damper. Compared to Rink type vane damper in current, we have focused on high efficiency with low price of that new developing damper. For selection of actuator, we have tried to find the propriety with our developing focus. Also, we have developed a jig of assembly processing for high productivity with quality, it caused the best assembly performance with heat-treated & processed parts.

• Corrosion Science and Technology
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• 제6권4호
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• pp.164-169
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• 2007

Hydrogen induced cracking (HIC) was studied phenomenologically and the effect of microstructure on HIC was discussed for the steels having two different levels of nonmetallic inclusions. Steels having different microstructures were produced by thermomechanically controlled processes (TMCP) from two different heats which had the different level of nonmetallic inclusions. Ferrite/pearlite (F/P), ferrite/acicular ferrite (F/AF), ferrite/bainite (F/B) were three representative microstructures for all tested steels. For the steels with higher level of inclusions, permissible inclusion level for HIC not to develop was different according to steelmicrostructure. On the contrary, HIC occurred also at the martensite/austenite (M/A) constituents regardless of steel microstructure when they accumulated to a certain degree. It was proved that M/A constituents were easily embrittled by hydrogen atoms. Steels having F/AF is resistant to HIC at a given actual service condition since they covers a wide range of diffusible hydrogen content without developing HIC.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.359-361
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• 2008

Glasses in the $SnO_2-(50-x)P_2O_5-xB_2O_3$ system were examined as potential replacement for the PbO glass frits with low firing temperature for component materials of a plasma display panel. The glasses were evaluated for their structural and the thermal expansion coefficient, glass transition and glass softening temperatures and Vickers hardness as a function of the $B_2O_3$ content.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.268-269
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• 2006

The estimation of applicability $SrTiO_3:Pr^{3+}$, Al to a class low-voltage flat-panel displays based on field emission effect, which have average value anode voltage $U_a=300V$ and current density $j=100\;mA/sm^2$ at duty 240, has given positive result. In the same time observably for the most effective sample in similar conditions of excitation high brightness - more than $500\;Kd/m^2$ and linear brightness dependences from current density and voltage allows to decrease greatly the power which consumed by the device.

• International Journal of Advanced Culture Technology
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• 제4권4호
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• pp.1-5
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• 2016

In this paper, we present the study on the proposed design of a real-time transmission of a video from the drone to broadcasting station (OBVan) by using F8L10D-N LoRa Module. Nowadays, LoRa technology is proved to be the mass of low cost, long range machine-to-machine connectivity. Particularly in the field of broadcasting and communication system, F8L10D-N LoRa RF Module spread spectrum technology with long transmission distance and strong penetrative ability that is double stronger than traditional FSK as well as PSK modulation scheme.