• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.528-531
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• 2000

Deposition of PZT with UV laser ablatio was applied for realization of thin film sensors and actuators. Deposition rate of more than 20nm/min was attained by pulsed KrF excimer laser deposition, which is fairly better than those obtained by the other methods. Perovskite phase was obtained at room temperature deposition with Fast Atom Beam(FAB) treatment and annealing. Smart MEMS(Micro electro-mechanical system) is now a suject of interest in the field of micro optical devices, micro pumps, AFM cantilever devices etc. It can be fabricated by deposition of PZT thin films and micromachining. PZT films of more than 1 micron thickness is difficult to obtain by conventional methods. This is the reason why we applied excimer laser ablation for thin film deposition. The remanent polarization Pr of 700nm PZT thin film was measured, and the relative dielectric constant was determined to about 900 and the dielectric loss tangent was also measured to be about 0.04. XRD analysis shows that, after annealing at 650 degrees C in 1 hour, the perovskite structure would be formed with some amount of pyrochlore phase, as is the case of the annealing at 750 degrees C in 1 hour.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권5호
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• pp.396-401
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• 1999

In this study, $Ar^+$ ion laser etching process of single/poly-crystalline Si with $CCl_2F_2$ gas is investigated for MEMS applications. In general, laser direct etching process is useful in microelectronic process, fabrication of micro sensors and actuators, rapid prototyping, and complementary processing because of the advantages of 3D micromachining, local etching/deposition process, and maskless process with high resolution. In this study, a pyrolytic method, in which $CCl_2F_2$ gasetches molten Si by the focused laser, was used. In order to analyze the temperature profile of Si by the focused laser, the 3D heat conduction equation was analytically solved. In order to investigate the process parameters dependence of etching characteristics, laser power, $CCl_2F_2$ gas pressure, and scanning speed were varied and the experimental results were observed by SEM. The aspect ratio was measured in multiple scanning and the simple 3D structure was fabricated. In addition, the etching characteristics of $6\mum$ thick poly-crystalline Si on the insulator was investigated to obtain flat bottom and vertical side wall for MEMS applications.

• 한국재료학회지
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• 제23권9호
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• pp.477-482
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• 2013

We investigated the detection properties of nitrogen monoxide (NO) gas using transparent p-type $CuAlO_2$ thin film gas sensors. The $CuAlO_2$ film was fabricated on an indium tin oxide (ITO)/glass substrate by pulsed laser deposition (PLD), and then the transparent p-type $CuAlO_2$ active layer was formed by annealing. Structural and optical characterizations revealed that the transparent p-type $CuAlO_2$ layer with a thickness of around 200 nm had a non-crystalline structure, showing a quite flat surface and a high transparency above 65 % in the range of visible light. From the NO gas sensing measurements, it was found that the transparent p-type $CuAlO_2$ thin film gas sensors exhibited the maximum sensitivity to NO gas in dry air at an operating temperature of $180^{\circ}C$. We also found that these $CuAlO_2$ thin film gas sensors showed reversible and reliable electrical resistance-response to NO gas in the operating temperature range. These results indicate that the transparent p-type semiconductor $CuAlO_2$ thin films are very promising for application as sensing materials for gas sensors, in particular, various types of transparent p-n junction gas sensors. Also, these transparent p-type semiconductor $CuAlO_2$ thin films could be combined with an n-type oxide semiconductor to fabricate p-n heterojunction oxide semiconductor gas sensors.

• 한국정보통신학회논문지
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• 제20권12호
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• pp.2310-2316
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• 2016

본 논문에서는 격자 공정 중에 KrF 엑시머 UV 레이저 노출시간에 따른 광섬유 브래그 격자의 $Co^{60}$ 감마방사선 영향을 연구하였다. 광섬유 브래그 격자는 게르마늄이 첨가된 일반 광섬유를 이용하였으며, UV KrF 엑시머 레이저 노출시간(30, 60, 90, 120초)을 달리하여 제작하였다. 제작된 광섬유 브래그 격자에 106 Gy/min 선량률로 총 선량 34.3 kGy 감마선을 조사한 후 방사선에 의한 온도감도 계수와 브래그 파장 변화를 분석하였다. 실험결과를 통하여, 격자 공정을 위한 UV 레이저 노출시간이 광섬유 브래그 격자의 방사선 민감도에 큰 영향을 줄 수 있다는 것을 확인하였다. 레이저 노출조건 변화에 따른 방사선에 의한 광섬유 브래그 파장의 변화는 최대 50 % 이상의 차이를 보였다.

• 한국항해항만학회지
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• 제30권10호
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• pp.839-845
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• 2006

선박 접안을 돕기 위해 레이저 접안 장치는 부두에 설치된 레이저 센서로부터 선박까지의 거리를 센티미터 수준의 정확도로 측정하여 제공한다. 그러나, 레이저 접안 장치는 레이저 센서의 정확한 설치 위치를 알아야 하고, 선박이 접안하는 부두의 전 범위를 다룰 수 있도록 설치되어야 하며, 부두의 선적 및 하역 환경, 조수의 변동을 고려해야 하는 문제가 있다. 특히 레이저 센서 거리 측정기는 가격이 비싸고, 거리를 측정할 수 있는 범위가 좁다는 단점이 있다. 레이저 접안 장치가 지닌 이상과 같은 문제를 해결하기 위한 방법으로 제안된 방법이 반송파보정 측위 기법이다. 본 논문에서는 상대 수평측위 정확 희석도 시뮬레이션을 통하여 레이저 접안 장치가 지닌 문제를 해결하기 위해 기존에 제안된 반송파 보정 측위기법이 연속성을 갖는 센티미터 정확도의 측위 서비스가 어려움을 보이고, 이를 해결하기 위한 방법으로 의사위성 보강 측위기법을 제안한다. 본 논문은 의사위성을 반송파 보정 측위성능 향상을 위해 사용하며, 제안한 측위기법이 기존에 반송파 보정 측위기법과 달리 연속성을 갖는 센티미터 정확도의 측위 서비스가 가능함을 보인다. 또한 제안한 측위기법이 선박 자동접안을 위해 요구하는 측위성능을 만족시키는 기법임을 필드시험을 위해 구축한 테스트 베드에서 확인한다.

• 융합신호처리학회논문지
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• 제11권4호
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• pp.338-344
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• 2010

선박 블록의 용접 공정에서는 용접선의 양쪽 끝이 벽에 의해 막혀있는 경우가 많다. 본 연구에서는 이러한 벽이 있는 환경에서 맞대기 용접의 자동화를 위한 용접선 검출 시스템을 개발하였다. 용접선 검출 시스템은 벽에서 캐리지의 위치를 측정하고, 초층의 용접선을 검출하게 된다. 시스템은 레이저 변위센서와 초음파센서로 구성되어 있다. 레이저 변위센서는 모터에 의해 회전 왕복 운동하며 용접 모재까지의 거리를 측정하게 되고, 초음파센서는 양쪽 벽면까지의 거리를 측정한다. 초음파센서로 측정된 거리정보를 활용하여 용접선의 X(주행)좌표와 용접 시작 및 끝 위치를 판별한다. 그리고 레이저 변위센서에 의해 측정된 거리정보와 센서의 자세정보를 활용하여 용접선의 Y(위빙), Z(높이)좌표를 검출하게 된다. 용접선 검출 시스템은 용접 캐리지와 독립적인 구동을 위해 DSP를 이용하여 별도의 제어기를 구성하였다. 용접 도중 용접선 검출 시스템과 용접 토치(Torch)와 간섭을 피하고, 측정 불가능한 구간이 발생하지 않도록 용접선 검출 시스템을 캐리지의 양쪽에 부착할 수 있게 설계하였다. 최종적으로 용접 캐리지에 부착하고 실험을 수행하여 개발된 용접선 검출 시스템의 효용성을 확인하였다.

• 전기학회논문지
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• 제59권5호
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• pp.922-926
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• 2010

We have investigated the grating coupled surface plasmon resonance (GC-SPR) sensors using ZnO nano-grating structures to enhance the sensitivity of an SPR sensor. The GC-SPR sensors were analyzed using the finite-difference time-domain method. The optimum resonance angles of 49 degrees are obtained in the 150 nm wide grating structure with a period of 300 nm for the ZnO thickness of 30 nm. Then, the ZnO nano-grating patterns were fabricated by using laser interference lithography. The measured resonance angle of nano-grating patterns was around 49 degrees. Here, an enhanced evanescent field is obtained due to the surface plasmon on the edge of the bandgap when the ZnO grating structures are used to excite the surface palsmon.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.241-246
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• 2002

Usually vibration properties are obtained from frequency response functions or impulse response functions of a system. Since the contact type sensors can affect the characteristics of vibrating systems, the non-contact type sensors such as laser Doppler vibrometer (LDV) are being widely used. Currently researches are being carried out in terms of modal analysis using a scanning vibrometer. For the continuous scan; the Chebyshev demodulation (or polynomial) is apparently suggested to extract the mode shapes. With single frequency sinusoidal excitation, this approach is well fitted. In this research, the Chebyshev demodulation technique has been applied to the impact excitation case. The vibration of the tested structure is modeled using impulse response functions. The technique is also adopted to the random excitation case. In order to verify the technique, a simply supported beam was chosen as the test rig. The calculation modules are developed by using MATLAB$\^$(R)/ in WindowsNT$\^$(R)/ environment.

• 센서학회지
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• 제20권1호
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• pp.8-13
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• 2011

We present measurements of the Brillouin frequency shift in an optical fiber using a 1550 nm distributed feedback laser diode(DFB-LD) as a light source. By modulating the probe light with an electro-optic modulator, we confirm the stimulated Brillouin gain spectrum(BGS) and spontaneous BGS using the coherent detection method. We also confirm the applicability of the technique to distributed temperature sensors that measure the change in Brillouin frequency shift due to temperature variations.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.55.1-55.1
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• 2012

In the first part of this talk, I will introduce an effort to use gold nanoparticles and UO22+ (uranyl) specific DNAzyme for development of highly sensitive and selective colorimetric uranyl sensors. In addition, I will discuss how DNA aptamers can be delivered by nanoparticles to cancer cell nucleus and released by ultrafast femtosecond pulsed laser for targeted cancer therapy. Finally, I will show how proteins such as streptavidin and myoglobin, or nanoparticles can be precisely aligned on DNA with nanometer resolution via backbone-modified phosphorothioate DNA and bifunctional linkers. These interesting functional and structural properties of DNA can provide new opportunities to develop dynamic DNA structures for potential use as intracellular sensors and drug delivery agents.