• Transactions on Electrical and Electronic Materials
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• v.7 no.6
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• pp.301-304
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• 2006

We studied the nematic liquid crystal (NLC) aligning capabilities using the new alignment material of the SiC (Silicon Carbide) thin film. The SiC thin film exhibits good chemical and thermal stability. The good thermal and chemical stability make SiC an attractive candidate for electronic applications. A vertical alignment of nematic liquid crystal by atomic beam exposure on the SiC thin film surface was achieved. The about $87^{\circ}$ of stable pretilt angle was achieved at the range from $30^{\circ}\;to\;45^{\circ}$ of incident angle. Consequently, the vertical alignment effect of liquid crystal electro-optical characteristic by the atomic beam alignment method on the SiC thin film layer can be achieved.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.398-398
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• 2007

The Liquid Crystal (LC) alignment uniformity is very important in LC devices. The alignment mechanism of LC molecules on a rubbed polyimide (PI) surface is very important for both LC fundamental research and application. So, Generally a rubbing method to align LC has been widely used to mass-produce LCD panels. But because rubbing method is contact method between rubbing fabric and indium-tin-oxide glass or flexible substrate, rubbing method has some defects, such as the electrode charges and the creation of contaminating particles. Thus we strongly recommend a non-contact alignment technique for getting rid of some defects of rubbing method. Most recently, the LC aligning capabilities achieved by ion-beam exposure on the organic and nonorganic thin film surface have been reported successfully. In this research, we studied the tilt angle generation and electro-optical performances for a NLC on homeotropic polyimide surfaces with ion-beam exposure. The LC aligning capabilities of a nematic liquid crystal (NLC) on a homeotropic PI surface using a new ion-beam method were studied. On the homeotropic PI surface, the tilt angle of the NLC by exposure ion-beam had a tendency to decrease as increased ion-beam energy density. And, on the homeotropic PI surface, the alignment character of the NLC with respect to ion-beam energy was good. And we achieved satisfactory result for EO character.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1155-1158
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• 2004

Various inorganic alignment layers of nematic liquid crystal (NLC) molecules were investigated. Ar ion beam (IB) irradiation was utilized for alignment method and homogenous and homeotropic orientations with tilt angle were obtained on the suitable inorganic thin films. Proper doping materials were added to diamond-like carbon (DLC) films. In the case of homogeneous alignment, nitrogen doping affected the increase of pretilt angle, while the fluorine bonding in the DLC films was induced the tilted homeotropic alignment cause its extreme hydrophobic property. These results showed that ion beam irradiation method could be applied to the various alignment mode of NLC such as IPS, TN and MVA.

• Transactions on Electrical and Electronic Materials
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• v.8 no.6
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• pp.265-267
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• 2007

The liquid crystal(LC) aligning capabilities of a nematic liquid crystal(NLC) on a homeotropic polyimide(PI) surface using a new ion-beam method were studied. Exposure ion-beam of $45^{\circ}$ incidence angle shows a good LC alignment of the NLC on the homeotropic PI surface. Also, on the homeotropic PI surface, the tilt angle of the NLC by exposure ion-beam of $45^{\circ}$ incidence angle had a tendency to decrease as increased ion-beam energy density. And, on the homeotropic PI surface, the alignment character of the NLC with respect to ion-beam energy was good at 1500 eV. And we achieved satisfactory result for EO character.

• Korean Journal of Optics and Photonics
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• v.32 no.1
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• pp.1-8
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• 2021

We have studied a tiled-aperture coherent-beam-combining system based on constructive interference, as a way to overcome the power limitation of a single laser. A 1-watt-level, 3-channel coherent fiber laser and a 3-channel fiber array of triangular tiling with tip-tilt function were developed. A monitoring system, phase controller, and 3-channel phase modulator formed a closed-loop control system, and the SPGD algorithm was applied. Eventually, phase-locking with a rate of 5-67 kHz and peak-intensity efficiency comparable to the ideal case of 53.3% was successfully realized. We were able to develop the essential elements for a tiled-aperture coherent-beam-combining system that had the potential for highest output power without any beam-combining components, and a multichannel coherent-beam-combining system with higher output power and high speed is anticipated in the future.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.339-341
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• 2006

This paper proposes a method of container position measurement using automatic landing system that is estimated by a laser range finder. In the most of container position measurement methods, CCD cameras or laser scanners have been used to get the source data. However those sensors are not only weak for disturbances, for examples, the light, fog, and rain, but also the system cost is high. When the spreader arrives the goal position, it is still swung by inertia or by wind effect. In this paper, the spreader swung data have been used to find the container position. The laser range finder is equipped in the front side of spreader. It can measure distance and relative position between spreader and container. This laser range finder can be rotated as desired by a motor. And a tilt sensor is equipped on the spreader to measure spreader sway. We estimate the relative position information between the spreader and a container using the laser range finder and tilt sensor through the geometrical analysis.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2299-2301
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• 2001

광 디스크의 용량을 증가시기키 위해선, 레이저 다이오드의 단파장화와 렌즈의 개구수 증가가 수년 동안 시도되어왔다. 불행히도 이러한 노력들은 디스크 틸트(tilt)로 인해 야기되는 코마(coma) 수차로 인한 부작용을 유발하였다. 이런 문제를 해결하기 위해, 램(random access memory, RAM) 디스크의 경우 몇 가지 검출과 보상 방법이 제안되었다. 그러나, 롬(read only memory, ROM) 디스크의 경우 아직까지 뚜렷한 해결책이 제시되지 않고 있다. 본 논문에서는 8분할 광 검출기에 의해 생성되는 차동 위상 검출(differential phase detection, DPD) 신호를 이용한 고밀도 롬 디스크에서 래디얼(radial) 틸트를 검출하는 방법을 제안한다. 3축 렌즈 구동형 액츄에이터(actuator)를 이용하여 개발한 래디얼 틸트 서보로 검출된 래디얼 틸트를 보상한다. 액츄에이터의 회전이 트래킹(tracking) 서보(servo)에 미치는 영향을 소개한다. 끝으로 제안된 방법의 유용성을 고밀도 롬 드라이브에 대한 실험을 통해 검증한다.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1775-1780
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• 2005

One of the most important factors so that mobile objects can achieve their purpose is the information about their positions. In this paper, we propose an improved beacon system, to which ultrasonic sensors are attached, for the indoor localization of mobile objects. We have researched so that it can cover the wider space and estimate more accurate positions than the existent beacon systems. The existent beacon systems have the constraint that one beacon cannot cover wide area since ultrasonic sensors have limits in the angle of signal (beam-angle) on which their signal strength depends. Hence, we used the active beacon which consists of a pan-tilt mechanism and a beacon module. The active beacon system can always aim at mobile objects in order to transmit the strongest signal of the ultrasonic sensors into the objects using the pan-tilt mechanism. In addition, this system is inexpensive because it can decrease the number of beacons by about a half of the beacons of the existent system. Finally, the results show what is the difference between the active beacon system and existent beacon systems, and how accurate it is.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.10
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• pp.1128-1136
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• 2012

In this paper, we propose an electrically tilting system based on a null-steering in order to solve the problem of the shadowing loss caused by the mechanically tilted antenna system in mobile services. Especially, we improve the downward shadowing loss by eliminating or moving the vertical beampattern nulls between $-30^{\circ}{\sim}0^{\circ}$ to be able to tilt the downward beampattern between $-10^{\circ}{\sim}0^{\circ}$. The antenna has 14.5 dBi gain and side lobe level (SLL) is lower than -18 dB within downward tilting range. The isolation of polarization is greater than 30 dB when running in electric tilt down to $-10^{\circ}$. To verify this paper, we made the base-station antenna for W-CDMA and beam tilting devices, and verified the performances.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04a
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• pp.44-44
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• 2008

To date, rubbing has been widely used to align LC molecules uniformly. Although rubbing can be simple, it has fundamental problems such as the generation of defects by dust and static electricity, and difficulty in achieving a uniform LC alignment on a large substrate. Therefore, non contact alignment has been investigated. Ion beam induced alignment method, which provides controllability, nonstop process, and high resolution display. In this study, we investigated liquid crystal (LC) alignment with ion beam (IB) that non contact alignment technique on polyimide and electro-optical characteristics of twisted nematic (TN)-liquid crystal display (LCD) on the polyimide under various ion beam angles. In this experiment, Polyimide layer was coated on glass by spin-coating and Voltage-transmittance(VT) and response time characteristics of the TN cell were measured by a LCD evaluation system. The good characteristics of the nematic liquid crystal (NLC) alignment with the ion beam exposure polyimide surface was observed. The tilt angle of NLC on the PI surface with ion beam exposure can be measured under $1^{\circ}$ for all of irradiation angles. In addition, it can be achieved the good EO properties, and residual DC property of the ion beam aligned TN cell on polyimide surface.