• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.417.1-417.1
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• 2014

본 연구에서는 갭 사이즈가 조절된 나노갭 소자[1]에 유기영동법을 이용하여 수용액 환경 내에 있는 금속 나노입자(금 나노입자)를 검출하였다. 수백 나노미터 사이즈로 제작된 나노갭 전극에 도금법으로 금을 성장시켜 갭 사이즈를 조절하고, 이로부터 전기장의 기울기를 극대화 할 수 있는 나노갭 소자를 제작함으로써 저농도 금 나노입자 검출의 효율성을 높였다. 제작된 나노갭 소자에 교류 신호를 이용한 유기영동법을 도입하여 수용액 환경 내 입자의 움직임을 제어하였다. 본 연구의 목표인 저농도 금 나노입자의 검출을 위해서는 100 kHz의 주파수를 이용하는 것이 가장 적절함을 실험을 통해 확인하였으며, 갭 사이즈가 조절된 나노갭 소자를 이용하여 전기장의 기울기를 극대화하고 입자의 움직임을 제어함으로써 50 aM의 저농도 금 나노입자를 검출할 수 있었다. 나노갭 소자를 이용한 금속 나노입자 검출에 관연 연구는 환경오염물질 검지용 입자센서 및 바이오센서 분야에 응용이 가능할 것으로 예상된다.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2006.10a
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• pp.120-125
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• 2006

본 연구에서는 기존의 레이저 변위센서 대신 접촉형 변위센서를 이용하여 마스크-기판간 갭 간격 및 평형 조절 장치를 구현함으로써 기판의 표면 상태에 관계없이 정확한 마스크-기판간 갭의 조정, 평형 유지가 가능하도록 하였다.

• Proceeding of EDISON Challenge
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• 2014.03a
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• pp.439-441
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• 2014

단층 $MoS_2$는 현재 트랜지스터나 LED등에 활용을 연구중인 물질이다. 단층 $MoS_2$의 밴드구조는 약 1.8eV의 직접 밴드갭을 보이는 반도체로 알려져있다. 이 물질을 소자에 활용할 때 고유의 1.8 eV 직접 밴드갭을 이용한다. 다양한 분야에 소자로 응용되기 위해서는 밴드갭을 조절이 필요하다. 그래서 $MoS_2$의 밴드갭을 조절하는 연구가 행해져 왔는데 그 중 하나가 수소흡착 방법이다. 수소를 단층 $MoS_2$에 흡착시키면 금속 밴드구조를 보인다고 알려져 있다. 본 연구에서는 DFT (Density Functional Theory) 계산을 통하여 밴드갭을 조절하는 다른 방법 중에 하나인 역학적인 힘에 의해 전기적인 특성의 변화에 대한 기초연구를 진행하였다. 단층 $MoS_2$에 in-plane 방향으로 isotropic strain을 주었을 때 밴드갭이 0.68 eV에서 1.89 eV까지 변하는 것을 확인했다. 우리는 단층 $MoS_2$는 약간의 strain에도 밴드갭크기가 다소 많이 변할 뿐만 아니라 직접 밴드갭이 간접 밴드갭으로 변하는 것을 보였다. 심지어 10%정도 strain을 주면 금속으로 변할 것으로 예상된다. 밴드갭이 변하는 성질을 이용하여 센서등 여러 어플리케이션에 단층 $MoS_2$를 활용할 수 있을 것으로 예상된다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.7
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• pp.1326-1331
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• 2006

Weld root gap is a important fact of a falling-off weld quality in various kind of weld defect. The welding quality can be controlled by monitoring important parameters, such as, the Arc voltage, welding current and welding speed during the welding process. Welding systems use either a vision sensor or an Arc sensor, both of which are unable to control these parameters directly. Therefore, it is difficult to obtain necessary bead geometry without automatically controlling the welding parameters through the sensors. In this paper we propose a novel approach using neural networks for detecting and monitoring of weld root gap and bead shape. Through experiments we demonstrate that the proposed system can be used for real welding processes. The results demonstrate that the system can efficiently estimate the weld bead shape and detect the welding defects.

• Ceramist
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• v.4 no.5
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• pp.29-34
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• 2001

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.2
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• pp.155-161
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• 2016

This paper proposes a novel fabrication method for a capacitive type micro-accelerometer with uniform nano-gap using photo-assisted electro-chemical etching. The sensitivity of the accelerometer should be improved while the electrodes between the inertial mass and the sensing comb should be narrowed. In this paper the nano-gap trench structure is fabricated using the photo-assisted electrochemical etching method. The sensor was designed and analysed using ANSYS simulator. The characteristics of the etching were observed according to the dc bias, the light intensity, the composition of the solution, the temperature of the solution, and the pattern pitch variation. The optimum etching conditions were dc bias of 2V, Blue LED of 20mA, 49wt% HF:DMF:D.I.Water=1:20:10, the pattern pitch of $20{\mu}m$. Uniform trench structure with width of 344nm and depth of $11.627{\mu}m$ are formed using the optimum condition.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.7
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• pp.23-29
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• 2010

We propose an optical gas sensor, which consists of a hollow core photonic bandgap fiber (HC-PBGF) and fiber Bragg grating (FBG), for the detection of acetylene gas. The gas detection scheme is uniquely characterized by modulating the Bragg wavelength of the fiber Bragg grating around a selected absorption line of gas filled in the photonic bandgap fiber. In the measurement, a 2m-long HC-PBGF and FBG with a Bragg wavelength of 1539.02nm were used. The FBG was modulated at 2Hz. We demonstrated that the optical fiber gas sensor was able to selectively measure the 2.5% and 5% of acetylene gases.

• Proceedings of the Korean Vacuum Society Conference
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• 2006.08a
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• pp.44-44
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• 2006

• Korean Journal of Optics and Photonics
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• v.29 no.6
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• pp.268-274
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• 2018

In this study we suggest a humidity-sensitive color sensor using a one-dimensional photonic crystal and Hong Kong University of Science and Technology-1 (HKUST-1), which is a metal-organic framework (MOF) substance. One-dimensional photonic crystals have a photonic band gap, due to a periodic refractive-index change, and block and reflect light components in a specific wavelength band. The refractive index of HKUST-1 differs in dry and humid environments. Herein we designed a sensor using the presence of the photonic band gap, with FDTD simulation. As a result of optical analysis, the color conversion of the reflected light was superior to the color conversion of the transmitted light. When the center wavelength of the photonic band gap was 550 nm, the maximum peak value of the wet environment increased by a factor of about 9.5 compared to the dry environment, and the color conversion from achromatic to green was excellent as a sensor. The results of this study suggest the application of MOF materials to moisture sensors, and the nanostructure design of MOF materials will expand the applications to industrial devices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05a
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• pp.35-39
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• 2002

A defect detection test was performed for a conductor using a amorphous wire sensor head. A uniform magnetic field was applied in the space between the most inner conductors of a spiral-typed coil. The conductor with a defect was placed on the space between the most inner conductors of spiral-typed coil. The defect can be detected from the differences of induced voltage measured in the vicinity of gap of the conductor. The induced voltage difference of 2.5mV was measured in the gap vicinity of the 1mm thick conductor having 0.5mm gap in the frequency region of 100kHz~600kHz.