• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.278-279
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• 2007

본 논문에서는 메조포러스 백금 전극이 적용된 무효소 혈당센서를 실리콘 기판 위에 제작하여 향후 CMOS 회로와의 집적이 가능하도록 설계하였으며, 초소형 무효소 혈당센서 구조의 최적화를 위하여 동일한 면적에서 여러 가지 구조의 센서를 설계 및 제작을 하고 그 결과를 비교 분석하였다. 제작된 무효소 혈당센서는 3전극시스템으로 구성되고 그 특성은 작동전극과 타 전극사이의 간격에 가장 민감한 변화를 보였다. 최적화된 구조를 갖는 센서는 11.1mM glucose실험에서 12.9${\mu}A$의 응답전류를 얻었으며 이 값은 효소를 사용한 센서와 비교하여도 월등히 큰 응답임을 알 수 있었다. 또한 제작된 센서들은 구조 최적화를 위하여 $9mm^2$로 동일한 크기로 실험을 하였지만, 이 크기는 응답전류가 매우 크므로 더욱더 소형화가 가능함을 알 수 있다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.548-551
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• 2010

A 150 lbf-thrust class micro turbojet engine has been developed. The engine could be applied to power plant for small aviation vehicle such as UAV, decoy and anti-radar missile and was designed with concepts that has small size, low-cost and high performance. A prototype was manufactured and performed the ground static test and high altitude test. This paper outlines the features and layout of 150 lbf turbojet engine and also describes the design characteristics and test results of the engine and components.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.45-48
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• 2008

Micro power generators have been studying to provide high power that micro systems require. Micro power generators need micro combustor. Swiss-roll combustor has been studied about scale, geometry, material. From previous study experiments have shown that swiss-roll combustors require thin walls with low thermal conductivity for maximum performance at small scales. In this work, polyimide combustors with low thermal conductivity and thin thickness are built and tested.

• Transportation Technology and Policy
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• v.9 no.5
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• pp.38-47
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• 2012

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05b
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• pp.47-47
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• 1992

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.2
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• pp.153-159
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• 2015

In this study, a 2-W micro-gas turbine engine was designed using micro-electro-mechanical systems (MEMS) technology, and analytical and experimental investigations of its potential under actual combustion conditions were performed. An ultra-micro-gas turbine contains a turbo-charger, combustor, and generator. A compressor, turbine blade, and generator coil were manufactured using MEMS technology. The shaft was supported by a precision computer numerical control machined air bearing, and a permanent magnet was attached to the end of the shaft for generation. An analysis found that the cooling effect of the air bearing and compressor was sufficient to cover the combustor heat, which was verified in an actual experiment.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.45-45
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• 2012

초고분자량 폴리에틸렌(UHMWPE)섬유는 현재까지 알려져 있는 섬유중 비강도가 가장 우수하며 강도 또한 최고 40g/d를 나타내는 슈퍼섬유중에 하나이다. UHMWPE섬유는 비교적 간단한 분자구조로 이루어져 있으며 높은 결정화도로 인해 광 안정성 및 자외선 저항성이 우수하며 내마모성도 뛰어나다. 이러한 특성으로 인해 최근 로프 및 어망 등의 산업적 용도 뿐만 아니라 익스트림 스포츠웨어를 포함한 의류소재에도 다양하게 적용되고 있다. 하지만 의류소재 적용에 앞서 초소수성으로 이루어진 분자구조와 낮은 내열성으로 인해 염색이 쉽지 않으며 다양한 색상을 구현하기가 힘든 실정이다. 현재 본 연구실에서는 이와 같은 문제점을 해결하기 위해 UHMWPE섬유에 염색이 가능한 염료를 개발하였으며 보다 다양한 색상을 구현하기 위해 연구를 진행 중이다. 현재 본 연구실에서는 UHMWPE섬유 염색에 있어 Blue, Red, Yellow, Magenta 계열의 색상구현이 가능하며 보다 심색화 된 색상을 구현함으로 인해 의류용 섬유소재 및 산업용 섬유소재에 다양하게 적용할 수 있도록 UHMWPE섬유용 염료합성 실험이 진행되고 있다. 안트라퀴논 및 아조계 염료에 초소수성 알킬체인을 치환함으로써 염료의 소수성을 증가시켜 초소수성 섬유인 UHMWPE섬유에 염착성을 증가시키고 높은 견뢰도 결과를 확보하였다. 또한 내열성이 낮은 특성에도 불구하고 염색 이후 UHMWPE섬유가 가지는 물성에는 큰 변화를 나타내지 않았다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.11
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• pp.971-978
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• 2016

Recent trends in miniaturization and lightness in portable electronics parts have driven developments in subminiature screws. This study aims to investigate the thread rolling process of a subminiature screw with an outer diameter and pitch of 1.0 and 0.25 mm, respectively. Finite element (FE) analyses were performed for the thread rolling process of symmetric and asymmetric screw threads. Through FE analyses, various process parameters, such as the horizontal and vertical die gap and the rolling stroke, were investigated in terms of the forming accuracy. The material flow characteristics in the thread rolling process of the symmetric and asymmetric screws were also discussed, and the relevant process parameters were determined accordingly. These simulation results were then reflected on real thread rolling processes, from which the symmetric and asymmetric screws could be formed successfully with allowable dimensional accuracy.

• Journal of Space Technology and Applications
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• v.4 no.1
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• pp.62-73
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• 2024

This study analyzed the effectiveness of orbital change through attitude change in nano-satellites operating in low Earth orbit (LEO) without thrusters, focusing on collision avoidance maneuvers. The results revealed that changes in the satellite's cross-sectional area significantly impact its in-track direction, influenced by the aspect ratio of cross-sectional area change and mission altitude. Notably, satellites at lower altitudes demonstrated significant reduction in collision risks with a small amount of attitude change. Through this study, it is judged that the changing the cross-sectional area through attitude maneuver is a sufficiently suitable method in the operation of nano-satellites without thrusters, and is expected to contribute to improving the safety of satellite operations in the New Space era.

• Journal of the Korean Association of Geographic Information Studies
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• v.24 no.4
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• pp.41-54
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• 2021

It is very essential to estimate the water body area using remote exploration for water resource management, analysis and prediction of water disaster damage. Hydrophysical detection using satellites has been mainly performed on large satellites equipped with optical and SAR sensors. However, due to the long repeat cycle, there is a limitation that timely utilization is impossible in the event of a disaster/disaster. With the recent active development of Micro satellites, it has served as an opportunity to overcome the limitations of time resolution centered on existing large satellites. The Micro satellites currently in active operation are ICEYE in Finland and Capella satellites in the United States, and are operated in the form of clusters for earth observation purposes. Due to clustering operation, it has a short revisit cycle and high resolution and has the advantage of being able to observe regardless of weather or day and night with the SAR sensor mounted. In this study, the operation status and characteristics of micro satellites were described, and the water area estimation technology optimized for micro SAR satellite images was applied to the Daecheong Dam basin on the Korean Peninsula. In addition, accuracy verification was performed based on the reference value of the water generated from the optical satellite Sentinel-2 satellite as a reference. In the case of the Capella satellite, the smallest difference in area was shown, and it was confirmed that all three images showed high correlation. Through the results of this study, it was confirmed that despite the low NESZ of Micro satellites, it is possible to estimate the water area, and it is believed that the limitations of water resource/water disaster monitoring using existing large SAR satellites can be overcome.