• Journal of Aerospace System Engineering
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• v.13 no.5
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• pp.24-31
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• 2019

In this study, we analyzed the cause of the burn out phenomenon in the power distribution system for aircraft and proposed the improvement method. The power distribution device for aircraft has an AC and DC, and there is a rectifier between the two devices. The capacitors in the power board burn out when the power is turned on and off. The main reason for this is the excessive voltage caused by the inductance built into the rectifier. The cases that can cause a failure are classified. The impact was analyzed and the solution was established through the experimental method.

• Aerospace Engineering and Technology
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• v.7 no.2
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• pp.76-81
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• 2008

The vibration test system of satellite environment test dept. has been used successfully for the vibration tests of a majority of korean space programs. To meet the recent needs of large size test facility available for the vibrational tests of the huge launch vehicles and satellites, KARI have developed the large size multi-electromagnetic shaking system with $3{\times}3m$ head expander system. The new system will consist of three electromagnetic shakers which has 160 kN thrust force individually, and be able to sustain up to 8 tons test load and 300 kNm overturing moment. This paper describes the design components in the development process of multi-excitation shaker system.

• Journal of the Microelectronics and Packaging Society
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• v.20 no.3
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• pp.59-62
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• 2013

Experimental analyses on the solder joint reliability of plastic ball grid array under harsh random vibration were presented. The chips were assembled on the daisy chained circuit boards for the test samples preparation, half of which were processed for underfill to investigate the underfill effects on the solder failures. Acceptance and qualification levels were applied for the solder failure tests, and the overall controlled RMS of the power spectrum densities of the steps were 22.7 Grms and 32.1 Grms, respectively. It was found that the samples survived without any solder failure during the tests, demonstrating the robustness of the packaging structure for potential avionics and space applications.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.7
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• pp.592-601
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• 2018

The GPS/INS integrated navigation system, which is one of the electronic equipments mounted on military aircraft store, can not directly receive GPS signals by the aircraft wing before the drop, so GPS navigation data is received from the aircraft and used for filter integration, afterwards, the integrated navigation is performed using the GPS information directly received through the antenna. In this case, it is possible to operate the mount in old aircraft without any modification of the aircraft when GPS data is transmitted using wireless. However, the delay occurs while the aircraft navigation data is transmitted to the integrated navigation filter of the aircraft store via wireless, which affects the time synchronization of the GPS measurement and the INS information, affecting the integrated navigation performance. In this paper, an algorithm to analyze and compensate the effect of generation and transmission delay that can occur when implementing GPS/INS integrated navigation system of aircraft store that receives GPS data via wireless.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.8
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• pp.648-653
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• 2014

Fly-wheel, gimbal antenna, mechanical gyro and cryocooler with moving parts generate a micro-vibration during their on-orbit operation. For the acquisition of high quality image of observation satellite, additional technical efforts are required to reduce the micro-vibration level from the vibration sources. In this study, we proposed a passive isolation system combined with a tuned mass damper-type energy harvester to generate electrical energy from the micro-vibration which has always been subjected to useless isolation objectives. The feasibility of the system has been investigated through the numerical simulation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.5
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• pp.358-363
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• 2019

If the EOIR equipment mounted on an unmanned aircraft transmits images and receives commands through a data link, there may be delays in data transmission depending on the transmission path of the data and the conditions of the ground equipment or wireless network. This increases the possibility of initial target LOCK-ON failure due to the difference between the time when the received image is viewed and the time when the image is taken. Therefore, this paper proposed a way to use frame indexes to synchronize with images, and to increase the success of target tracking by adding frame indexes to commands from the ground station.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.5
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• pp.449-455
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• 2015

Built-In-Test(hereafter: BIT) is necessary functionality for aircraft flight safety and it requires a high failure detection capacity of more than 95 % in the case of avionics equipment. The BIT coverage analysis is needed to make sure that BIT meets its fault diagnosis capability. FMECA is used a lot of for the BIT coverage analysis. However, in this paper, the BIT coverage analysis based on electronic components is introduced to minimize the analytical error. Further, by applying the failure mode of the electronic components and excluding electronic components that do not affect flight safety, the BIT coverage analysis can be more accurate. Finally, BIT demo was performed and it was confirmed that the performance of the actual BIT matches the analysis of BIT performance.

• Defense and Technology
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• no.11 s.129
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• pp.52-59
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• 1989

BAe사는 영국유수의 수출품제작회사로서 세계에서 손꼽히는 대규모 방산업체 가운데 하나이다. 이 회사는 군용 및 민간용 항공기, 유도무기, 방어용 장비, 우주시스템등 어느나라 보다도 더 많은 종류의 제품을 설계 및 제작하고 있다. 또한 자동차, 병기, 건설 및 전자산업에도 진출하여 세계 1백50개국에 고객을 확보하고 있고, 총 작업인원이 13만명을 상회하고 있다. 이 회사는 최근 고객에 대한 요구를 충족시키기 위해 전문성을 갖도록 독립적으로 회사를 재구성하였다. 방산분야를 볼 때 새로 통합된 조직은 영국 우주항공방산회사로서 3개회사(군용기회사, 동력학회사, 로얄병기회사 등)를 통해 광범위하고 복잡한 군사자원들을 결합시키고 있다

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.184-184
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• 2004

볼 나사는 반도체ㆍLCDㆍPDP 등 전자제품 조립장비 제조업체와 CNC 공작기계, 정밀측정기계, 직교좌표로봇, 반송장치, 항공기용 유압구동장치 대체품, 전동공구, 파워 steering, 테이블 개폐장치 등에서 구동 장치 및 물품의 이송을 위해 대부분 사용되는 중요한 기계요소 중의 하나이다. 그것은 회전운동을 직선운동으로 전환해주는 기구부에 들어가는 가장 중요한 부품이며, 원통형의 봉에 나선형의 그루브를 가공한 장축의 나사와 단축의 너트 사이에 볼을 게재시켜 축의 회전 시 적은 구름마찰로 인해, 너트부가 직선 운동하는데 원활 하게 만들어진 기계요소이다.(중략)

• Journal of the KSME
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• v.28 no.6
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• pp.525-529
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• 1988

고분자 및 복합재료 성형기술의 향상은 다른 재료의 생산기술에서 요구되는 것과 같이 고정밀 도를 성취하기 위한 기술, 전산기를 이용한 가공공정의 자동화, 풍부한 데이터베이스 및 소프트 웨어의 개발, 재료 및 성형장비의 표준화, 고급인력의 양성 등이 절대적인 필수조건이다. 필자는 아직 국내의 사정에 익숙하지 못해서 여러면에서 부족한 국내의 산업수준을 고려할 때 국내의 고분자관련산업도 많은 발전을 요구한다고 판단된다. 자동차, 전기전자, 우주항공 등 첨단산업 으로부터 장난감, 스포츠용품까지 널리 사용되는 고분자 재료의 가공기술 개발에 과감한 투자를 하여야 할 것으로 확신한다.