• Journal of Aerospace System Engineering
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• v.13 no.5
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• pp.65-71
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• 2019

In this study, as a part of the aging aircraft performance improvement project for which no design information is provided, a new type of blade antenna is installed on the main part of the aging aircraft, and the method of proving the fatigue life of the main part of the aircraft is reviewed and summarized. There are various methods to prove fatigue life according to the manufacturer and aircraft design conditions. The fatigue life prediction and damage tolerance range of the relevant site were obtained through related regulations and industry examples. From these results, the fatigue life of newly installed antennas around the main parts of the aging aircraft was evaluated and the maintenance period and criteria were set according to the damage tolerance.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.9
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• pp.784-793
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• 2017

A two-axis gimbal-type X-band antenna mounted on an observation satellite can efficiently transmit high-capacity image data to a ground station regardless of both the satellite position and the orbital motion. However, this X-band antenna induces unnecessary micro-jitter which can degrade the image quality of the high-resolution observation satellite. Therefore, to achieve the high-resolution image quality from the observation satellite, micro-jitters have been required to be isolated. In this study, to resolve aforementioned drawback, we proposed blade gear using a shape memory alloy (SMA) applied to azimuth stage of X-band antenna. To investigate the rotational basic characteristics of the proposed SMA blade gear, we performed rotational static loading test. Futhermore, to evaluate the cycle to failure of the gear, accelerated life test was conducted. The temperature test was conducted to confirm rotational basic characteristics at various temperature conditions. To verify the isolation performance for micro-jitter, we performed micro-jitter measurement test.

• Journal of Aerospace System Engineering
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• v.12 no.2
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• pp.46-58
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• 2018

A two-axis gimbal-type X-band antenna is widely used to transmit bulk image data from high-resolution observation satellites. However, undesirable microvibrations induced by driving the antenna should be attenuated, because they are a main cause of image-quality degradation of the observation satellite. In this study, a pseudoelastic memory alloy (SMA) gear was proposed to attenuate the microvibrations by driving the antenna in an azimuth angle. In addition, the proposed gear can overcome the limitations of the conventional titanium blade gear, which is not still enough and is vulnerable to plastic deformations under excessive torque. To investigate the basic characteristics of the proposed SMA mesh washer gear, a static load test was performed on the thickness of the SMA mesh washer and the rotation of the gear. Moreover, The microvibration measurement test demonstrated that the SMA mesh washer gear proposed in this study is effective for microvibration attenuation.

• Journal of fish pathology
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• v.11 no.2
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• pp.119-127
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• 1998

Two species of the parasitc copepods, Clavellopsis hugu (Lemaeopodidae; Siphonostomatoida) and Taeniacanthus yamagutii (Taeniacanthidae; Poecilostomatoida) from cultured Korean fish, Takifugu obscurus, is described and reported for the first time in Korea. The parasite was recovered from the buccal cavity, nose and skin. Clavellopsis hugu is easily identified by the body shape, 2nd antenna, mandible and 2nd maxillae. In female, cephalothorax flexed dorsally, second antenna biramose, mandible with serrate blade, second maxillae completely fused at base of cephalothorax. In male, cephalothorax and trunk fused into an ovoid, two pairs of maxillipeds chelate. The most distinctive features of Taeniacanthus yamagutii are terminal process of second maxilla stout, maxilliped claw with conspicuous digitiform process at base and a setiform element at the tip of each exopod spine of legs 2-4. Both parasitic copepod species are new to the Korean fauna. The korean fish, Takifugu obscurus should be considered as an additional host of this species because these parasite were recovered from the western coast of Korea (Boryung Hatchery).

• Journal of Digital Convergence
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• v.14 no.1
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• pp.195-201
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• 2016

In this paper, we present the direction finding accuracy of correlative interferometer method and amplitude-phase comparison method. Spiral antennas are used for amplitude-phase comparison method and blade antennas are used for correlative interferometer method. Those are made for uniform circular array (UCA) direction finding antenna systems. We simulate the accuracy of azimuth angle with 3 antennas UCA when SNR is 20 dB and baseline is 0.5 wave length. Correlative interferometer method has better accuracy than amplitude-phase comparison method.