• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.939-940
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• 2008

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.597-598
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• 2009

• 한국정밀공학회지
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• 제28권3호
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• pp.383-388
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• 2011

The cold hollow cathode gas ion source is under development for multi aperture focused ion beam (FIB) system. In this paper, we describe the cold hollow cathode ion source design and the general ion source performance using Ar gas. The glow discharge characteristics and the ion beam current density at various operation conditions are investigated. This ion source can generate maximum ion beam current density of approximately 120 mA/$cm^2$ at ion beam potential of 10 kV. In order to effectively transport the energetic ions generated from the ion source to the multi-aperture focused ion beam(FIB) system, the einzel lens system for ion beam focusing is designed and evaluated. The ions ejected from the ion source can be forced to move near parallel to the beam axis by adjusting the potentials of the einzel lenses.

• 대한전자공학회논문지TC
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• 제40권11호
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• pp.77-84
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• 2003

본 논문에서는 위상변위기를 제어하여 스파이럴에 연결되는 급전선의 위상차를 조절함으로써 이중 주파수 대역에서 빔 모양을 선택할 수 있는 다기능 마이크로스트립 스파이럴 안테나를 제안하였다. 이 안테나는 하위 주파수 대역에서 안테나 평면에 수직한 고정빔, 그리고 상위 주파수 대역에서 수직빔, 코니컬빔, 두 가지의 기운빔 등의 4가지의 서로 다른 빔 패턴을 얻을 수 있으며 각 주파수 대역에서 10% 이상의 대역폭을 가진다 한쪽 방향으로의 복사를 제거하기 위하여 전자파 흡수체를 부착하였으며, 실측을 통하여 위상천이에 따른 빔 패턴을 확인하였다.

• Journal of Astronomy and Space Sciences
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• 제23권1호
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• pp.19-28
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• 2006

The noise temperature of existing millimeter-wave receivers is already within two or three times quantum noise limit. One of practical ways to increase the observation speed of single dish radio telescope without longer integration time is use of multi-beam focal plane array receiver as demonstrated in several large single dish radio telescopes. In this context the TRAO (Taeduk Radio Astronomy Observatory), which operates a 143n Cassegrain radio telescope, is planning to develop a 4 x 4 beams focal plane array SIS receiver system for 86-115 GHz band. Even though millimeter-wave HEMT LNA-based receivers approach the noise temperature comparable to the SIS receiver at W-band, it is believed that the receiver based on SIS mixer seems to offer a bit more advantages. The critical part of the multi-beam array receiver will be sideband separating SIS mixers. Employing such a type of SIS mixer makes it possible to simplify the quasi-optics of receiver. Otherwise, an SSB filter should be used in front of the mixer or some sophisticated post-processing of observation data is needed. In this paper we will present a preliminary design concept and components needed for the development of a new 3 mm band multi-beam focal plane array receiver.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.160-161
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• 2005

It is important to manage artificial fish reefs with installation for restoration. The instruments of survey for artificial reefs condition(location, amount etc.) is Side Scan Sonar and Multi-beam sonar. The efficient and economic survey of the artificial reefs facility is the complete survey of the SSS(Side Scan Sonar) in all area first and then the survey of the artificial reefs by MBES(Multi Beam Echo Sounder) in the finding area.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.99-99
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• 2000

An effect ive filter algorithm that can manage radar beam pointing efficiently is needed to track multi-target in the air. For effective beam management the filter has lobe good enough to predict future position of target and based on this filter output radar beam is control led to point toward the predicted target position in the air. In this paper, we investigate the ${\alpha}$-${\beta}$ filter known for its brief filter structure with the steady-state Kalman filter gain, the ruv filter, and the coordinate-transformed filter that can decouple the measurement noise variance.

• International Journal of Aeronautical and Space Sciences
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• 제5권2호
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• pp.71-76
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• 2004

This paper describes the antenna analysis of the multi-beam for communicationsatellite. The design core parameters of the antenna system are optimal antennadiameter, feed horn type and hom size, F/D, and the coordinate of offset horns. Thepaper deals with the method to determine design core parameters of optimal antennadiameter, feed horn type and horn size. F/D, and the coordinate of offset horns, andthe performances of design result.

• Structural Engineering and Mechanics
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• 제21권3호
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• pp.351-367
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• 2005

Multi-span beams carrying multiple point masses are widely used in engineering applications, but the literature for free vibration analysis of such structural systems is much less than that of single-span beams. The complexity of analytical expressions should be one of the main reasons for the last phenomenon. The purpose of this paper is to utilize the numerical assembly method (NAM) to determine the exact natural frequencies and mode shapes of a multi-span uniform beam carrying multiple point masses. First, the coefficient matrices for an intermediate pinned support, an intermediate point mass, left-end support and right-end support of a uniform beam are derived. Next, the overall coefficient matrix for the whole structural system is obtained using the numerical assembly technique of the finite element method. Finally, the natural frequencies and the associated mode shapes of the vibrating system are determined by equating the determinant of the last overall coefficient matrix to zero and substituting the corresponding values of integration constants into the related eigenfunctions respectively. The effects of in-span pinned supports and point masses on the free vibration characteristics of the beam are also studied.

• 한국정밀공학회지
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• 제15권12호
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• pp.194-201
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• 1998

The beam rotating actuator has been developed. It can be utilized to improve the data transfer rate for the optical disk systems, Newly developed laser beam rotating actuator is applied to put multi-beam spots on more than one track on the optical disk simultaneously. The beam rotating actuator is made of piezoelectric ceramic bimorph as the form of cantilever, Piezoelectric actuators with high resolution, high stiffness and fast frequency response are widely assembled in micropositioning applications. Therefore, the actuator has above 50Hz natural frequency. Beam array is rotated using the dove prism in the end of beamrotator. The dynamic equation of beam rotating actuator is derived theoretically. The actuator is designed on the ground of this analysis. The performance of the beam rotating actuator is verified as the dynamics frequency performance is measured using the dynamic analyzer and sensor.