• 한국항공우주학회지
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• 제48권9호
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• pp.681-689
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• 2020

본 논문에서는 유도형 탄약의 모사 기체를 제작하고 공중에서 탄체에 롤축 회전을 인가한 뒤 롤축 저속 회전 중인 탄체의 롤각 추정 성능을 실험적으로 검증한 방법과 결과를 소개한다. 멀티로터형 무인기를 모선으로 사용해 유도형 탄약 모사 기체에 초기 속도와 고도를 부여하였으며 탄체 투하, 탄체 회전, 롤각 추정 및 안정화로 이어지는 비행 시험 시나리오를 통해 롤각 추정 결과를 분석한다. 약 200m의 고도에서 수평 방향으로 15m/s의 속력으로 탄체를 투하한 뒤 내부의 반동차(Reaction Wheel)를 사용하여 탄체를 회전시켰으며 특히, 상용 GPS/INS와의 비교를 통해 롤각 추정 결과를 제시한다. 아울러, 반동차를 이용하여 공중에서 탄체를 롤축 회전시키는 메커니즘들을 비교하고 실제 구현한 결과도 소개한다.

• 대한금속재료학회지
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• 제48권9호
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• pp.831-841
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• 2010

Indium tin oxide (ITO) nanopowders were synthesized by coprecipitation and the sol-gel method to prepare a stable dispersion of ITO nano-colloid for antistatic coating of a display panel. The colloidal dispersions were prepared by attrition process with a vibratory milling apparatus using a suitable dispersant in organic solvent. The ITO coating solution was spin-coated on a glass panel followed by the deposition of partially hydrolyzed alkyl silicate as an over-coat layer. The double-layered coating films were characterized by measuring the sheet resistance and reflectance spectrum for antistatic and antireflective properties.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 춘계학술발표강연 및 논문개요집
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• pp.211-211
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• 2003

PbTiO$_3$ 씨앗층을 이용하여 완화형 강유전체 Pb(Mg$_{1}$3/Ta$_{2}$3/)O$_3$ (PMT) 박막의 페로브스카이트 상안정화와 열처리 조건에 따른 미세구조변화, 이에 따른 전기적 특성 변화에 관하여 조사하였다. PbTiO$_3$ 박막을 스핀코팅법으로 3000 rpm에서 20초간(111) 방향으로 배향된 Pt / Ti / SiO$_2$/ Si 기판에 증착하여 안정화된 페로브스카이트 박막을 얻었다. 이렇게 제조된 PbTiO$_3$를 Buffer 층으로 사용하고 그 위에 Pb(Mg$_{1}$3/Ta$_{2}$3/)O$_3$를 박막을 Spin coating방법으로 증착한 후, 급속열처리 방법(RTA)으로 550- $650^{\circ}C$ 사이에서 열처리하였다. 제조된 박막의 열처리 온도에 따른 미세구조 변화와 결정성을 XRD, SEM, TEM으로 분석하였고 박막의 저온 강유전 특성을 RT66A를 이용하여 평가하였다. Pb(Mg$_{1}$3/Ta$_{2}$3/)O$_3$ 박막의 경우 씨앗층이 없는 경우에는 pyrochlore상이 주상이었지만 씨앗층을 사용한 경우 페로브스카이트 상이 주상임을 확인하였고 열처리 온도가 증가할수록 페로브스카이트상의 상대적 양이 증가함을 확인하였다. 미세구조와 상의 변화에 따른 전기적 특성 변화에 관하여 자세하게 논의할 것이다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 추계학술대회 논문집
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• pp.339-342
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• 1998

Ferroelectric L $a_2$ $Ti_2$ $O_{7}$(LTO) thin films were prepared by chemical solution deposition processes. Acetylacetone was used as chelating agent and nitric acid was added in the stock solution to control hydrolysis and condensation reaction rate. The LTO thin films were spin-coated on Pt/Ti/ $SiO_2$/(100)Si and Pt/Zr $O_2$/ $SiO_2$/(100)Si substrates. After multiple coating, dried thin films were heat-treated for decomposition of residual organics and crystallization. The role of acetylacetone in Ti iso-propoxide stabilization by possibly substituting $O^{i}$Pr ligand was studied by H-NMR. B site-rich impurity phase, i.e. L $a_4$ $Ti_{9}$ $O_{24}$, was found after annealing, where its appearance was dependent on process temperature indicating the possible reaction with substrate. Dielectric and other relevant electrical properties were measured and the results were compared between modified sol-gel and MOD processes.s.s.

• 대한전기학회논문지:시스템및제어부문D
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• 제49권8호
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• pp.459-466
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• 2000

In this paper, we propose an attitude controller for an unstructured object using CMG(Control Moment of Gyro) subsystem, which has a stabilizer function. The CMG subsystem consists of one motor for spinning the wheel and the other motor for turning the outer gimbal. While the wheel of CMG subsystem is spinning at high speed, applying force to the spin axis of the wheel leads the torque about the vertical axis. We utilize the torque to control the attitude of object in this study. For the stabilizer function, in additiion, holding the load at the current position, the power applied to the gimbal motor of CMG will be cut, which result in the braking force to stop the load by gyro effect. However, due to the gear reduction connected to outer gimbal, slow load motion cannot generate the braking force. Thus, in this study, we are willing to make a holding force by applying control power to the gimbal motor from the signal of piezoelectric gyroscopic sensor that detected the angular velocity of the load. These two features are demonstrated in experiment, carrying a beam with crane. As a result, load was started to rotate by controlling gimbal positiion and was stopped by turning off the gimbal power. Moreover, slow movement of the load was also rejected by additional control with gyroscopic sensor.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권1호
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• pp.38-44
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• 2003

In this study, the balance beam control subsystem, new type of construction machinery using the mechanism of CMG (control moment gyro), for the attitude control of an unstructured object such as a beam carried by a tower crane, is designed and implemented. The balance beam controller consists of a wheel spinning at high speed and an outer gimbal for controlling the attitude of the wheel. Two motors, one for the wheel and the other for the gimbal, are used. Applying force to the spin axis of the wheel, as an input of the system, leads the torque about the axis because of the gyro effects. This torque is used to control the attitude of the unstructured object in this study. For the stabilizer function, in addition, holding the load at the current position, the attitude of the wheel is freed by cutting the power applied to the gimbal motor of the balance beam controller, which result in the braking force to stop the load by gyro effect. The works presented here include the mechanical system of the balance beam controller, the remote controller, the servo controller and the control software for the system. We also present experimental results to show that the system we proposed is useful as a new construction machinery which can control the attitude of the beam hanging from a tower crane.

• 한국진공학회지
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• 제17권6호
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• pp.549-554
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• 2008

수소 플라즈마 처리된 유리 기판에 스핀 코팅 시스템을 이용하여 nickel chloride를 코팅하여 단백질칩 플레이트를 제조하였다. 다양한 플라즈마 처리 시간대에서 histidine tagged 단백질의 부착 능력 특성을 연구하였다. 유리 기판 표면에서 nickel chloride와 단백질 특성을 particle size analysis를 이용하여 관찰하였고, 단백질의 부착 능력 정도를 bio imaging analyzer system으로 측정하였다. 실험 결과에 따르면, 플라즈마 처리 시간이 증가할수록 단백질 부착 능력은 감소하는 것으로 나타났다. 기판 표면에서의 단백질 부착능력 특성에 관한 mechanism은 본문의 결과 및 토의에서 논의되었다. 플라즈마 처리된 단백질칩 기판에 대한 표면 안정화는 바이오센서 시장에서 큰 관심을 끌 것으로 기대된다.

• Bulletin of the Korean Chemical Society
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• 제30권1호
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• pp.205-213
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• 2009

This study reports on the geometry optimizations and electronic structure calculations for methyl pyropheophorbide (MPPa), tropolonyl methyl pyropheophorbides (TMPPa, ITMPPa), and cationic tropolonyl methyl pyropheophorbides ($TMPPa^+{{\cdot}BF_4}^-,\;ITMPPa^+{{\cdot}BF_4}^-,\;TMPPa^+,\;and\;ITMPPa^+$) using Local Spin Density Approximation (LSDA/ 6-31G*) and the Restricted Hatree-Fock (RHF/6-31G*) level theory. From the calculated results, we found that substituted cationic tropolonyl groups have larger structural effects than those of substituted neutral tropolonyl groups. The order of structural change effects is $ITMPPa^+ > ITMPPa^+{{\cdot}BF_4}^-$ > ITMPPa, as a result of the isopropyl group. Because it is an electron-releasing group, the substituted isopropyl group electronic effect on a 3-position tropolone increases the Highest Occupied Molecular Orbital and Lowest Unoccupied Molecular Orbital (HOMO-LUMO) energy gap. It was constituted that the larger the cationic characters of these photosensitizers, the smaller the HOMOLUMO band gaps are. The orbital energies of the cationic systems and the ions are stronger than those of a neutral system because of a strong electrostatic interaction. However, this stabilization of orbital energies are counteracted by the distortion of chlorin macrocycle, which results in a large destabilization of chlorin-based compound HOMOs and smaller destabilization of LUMOs as shown in TMPPa (ITMPPa), $TMPPa^+{{\cdot}BF_4}^- (ITMPPa^+{{\cdot}BF_4}^-),\;and\;TMPPa^+\;(ITMPPa^+)$ of Figure 6 and Table 6-7. These results are in reasonable agreement with normal-coordinate structural decomposition (NSD) results. The HOMO-LUMO gap is an important factor to consider in the development of photodynamic therapy (PDT).