• Journal of the Optical Society of Korea
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• v.7 no.3
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• pp.160-164
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• 2003

Materials processing by ultrashort pulsed laser is actively being applied to micromachining technology due to its advantages with regard to non-thermal machining. In this study, materials processing with ultrashort pulses was studied by using the high repetition rate of a 800 nm Ti:sapphire regenerative amplifier. This revealed that the highly precise micromachining of metallic thin film and bulk glass with a minimal heat affected zone (HAZ) could be obtained by using near damage threshold energy. Grooves with diffraction limited sub-micrometer width were obtained with widths of 620 nm on Cr thin film and 800 nm on a soda-lime glass substrate. The machined patterns were investigated through SEM images. We also phenomenologically examined the influence of variations of parameters and proposed the optimal process conditions for microfabrication.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.867-869
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• 2007

TinyOS기반 무선센서노드를 사용한 실시간 계측 데이터 측정 및 제어기술은 유비쿼터스 센서 네트워크 분야에 주로 사용되어 왔으나 다양한 응용이나 신뢰성 있는 무선 네트워크 연구 개발에 한계가 있는 것으로 알려져 있다. 본 논문에서는 ATMega128L을 장착한 최소 8대 이상의 nano-24 센서 노드모듈과 메모리 용량이 매우 제한적인 무선 센서 노드에 적합하다고 평가받고 있는 Nano-Q+를 사용하여 전시물 주변의 환경 정보를 실시간 측정하는 시스템을 구현하였다. 전시물 주변의 센서들은 하나의 PAN Coordinator를 중심으로 Start-Mesh 네트워크를 구성하여 환경 정보를 측정한다. 환경 정보를 전송 하기 위해 측정된 계측 데이터를 센서 네트워크의 PAN Coordinator 노드로부터 환경 모니터링 서버로 효율적으로 전송하기 위한 TCP기반 전송 프로그램을 구현하였다. 실험 결과 센서 노드 수와 관련된 PAN의 크기 및 샘플링 주기에 상관없이 안정적으로 계측 데이터 수신이 이루어짐을 확인 하였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.10
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• pp.1876-1882
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• 2008

Nano manipulator is used to manufacture Carbon NanoTube(CNT) tips. Using nano manipulator, operator attaches a CNT at the apex of Atomic Force Microscope(AFM) tip, which requires a mastery of mechanics and long manufacture time. Nano manipulator is installed inside a Scanning Electron Microscope(SEM) chamber to observe the operation. This paper presents a control scheme for horizontal axes of nano manipulator via processing SEM image. Edges of AFM tip and CNT are first detected, and the position information so obtained is fed to control horizontal axes of nano manipulator. That is, a visual servoing loop is realized to control the axes more precisely in nano scale.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.12
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• pp.19-24
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• 2003

• Journal of Powder Materials
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• v.14 no.5
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• pp.320-326
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• 2007

Ag-Cu alloy nano powders were fabricated by the electrical explosion of Cu-plated Ag wires. Ag wires of 0.2mm diameter was electroplated to final diameter of 0.220 mm and 0.307 mm which correspond to Ag-27Cu and Ag-68Cu alloy. The explosion product consisted of equilibrium phases of ${\alpha}-Ag$ and ${\beta}$-Cu. The particle size of Ag-Cu nano powders were 44 nm and 70 nm for 0.220 mm and 0.307 mm wires, respectively. The Ag-Cu nano powders contained less Cu than average value due to higher sublimation energy compared to that of Ag. As a result, micron-sized spherical particles formed from liquid droplets contained higher Cu content.

• Korean Journal of Materials Research
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• v.22 no.3
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• pp.155-158
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• 2012

In this work, AlON-$Al_2O_3$ coatings were prepared on Al2021 alloy by the electrolytic plasma processing (EPP) method. The experimental electrolytes include: 2 g/l NaOH as the electrolytic conductive agent, 10 g/l $Na_2AlO_2$ as the alumina formative agent, and 0.5 g/l $NaNO_2$, $NaNO_3$, and $NH_4NO_3$ as the nitride inducing agents. The effects of different nitrogen inducing agents were studied by a combined compositional and structural analyses of the ceramic coatings carried out by Xray diffractometry (XRD) and scanning electron microscopy (SEM) for the specimens EPP-treated at room temperature for 15 min under a hybrid voltage of 260 DC along with an AC 50 Hz power supply (200 V). Microhardness tests and wear tests were carried out to correlate the evolution of the microstructure and the resulting mechanical properties. Potentiodynamic polarizations and immersion corrosion tests were carried out in 3.5wt% NaCl water solutions under static conditions in order to evaluate the corrosion behavior of the coated samples. The results demonstrate that $NaNO_2$ is proven to be a good nitrogen inducing agent to produce high quality AlON-$Al_2O_3$ ceramic coatings.

• Macromolecular Research
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• v.16 no.5
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• pp.404-410
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• 2008

In order to obtain 'value added products' from polypropylene (PP)/waste ground rubber tire powder (WGRT) composites, PP/WGRT microcellular foams were prepared via supercritical carbon dioxide. The effects of blend composition and processing condition on the cell size, cell density and relative density of PP/WGRT micro-cellular composites were studied. The results indicated that the microcellular structure was dependent on blend composition and processing condition. An increased content of waste ground rubber tire powder (WGRT) and maleic anhydride-grafted styrene-ethylene-butylene-styrene (SEBS-g-MA) reduced the cell size, and raised the cell density and relative density, whereas a higher saturation pressure increased the cell size, and reduced the cell density and relative density. With increasing saturation temperature, the cell size increased and the relative density decreased, whereas the cell density initially increased and then decreased.

• Transactions of Materials Processing
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• v.20 no.1
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• pp.23-28
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• 2011

For the fabrication of nano patterned products manufacturing a nano patterned mold is needed in advance. The nano patterned stamper was fabricated by electroforming the AAO master with nickel. The surface of nickel-plated stamper had nano-patterned holes with the diameter of 73 nm and the depth of 83 nm. Hot embossing was used for forming P3HT sheet and the process factors of hot embossing were closer as pressure, temperature and time. In the present paper hot embossing experiments were performed to find the main process conditions to affect the replication ratio of nano patterns on surface of P3HT sheet. As a result, main contributing factors for the replication ratio of hot embossed pattern could be sequentially enumerated as pressure, temperature and time.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.632-635
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• 2003

As a process technology of nano pattern with a new conception for economic and practical technology of alternative nano process. process technologies such as Embossing, Imprinting. Molding and Inking are beginning to make its appearance. Among these alternative processes, nano mold process is a process that is of benefit to mass production and keeps excellency of reproduction and high quality of parts. In this study, we experienced micro precision machining technology of nano stamper for the injection mold of optical disk with big capacity. Especially, Flatness and uniformity are important for nano stamper with global area, for the purpose of developing polishing technology of micro precision of Back polishing only being used for nano stamper, we carried out a basic study to secure flatness standards

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.251-252
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• 2007

Nano manipulator is used to manufacture Carbon NanoTube(CNT) tips. Using nano manipulator operator attaches a CNT at the end of Atomic Force Microscopy(AFM) tip, which requires a master mechanic and long manufacture time. Nano manipulator is installed inside Scanning Electron Microscopy (SEM) chamber to observe the operation. This paper presents a control of horizontal axis of nano manipulator via processing SEM image. Edges of AFM tip and CNT are first detected, the position information so obtained is fed to control horizontal axis of nano manipulator. To be specific, visual servoing loop was realized to control the axis more precisely.