• Current Industrial and Technological Trends in Aerospace
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• v.7 no.2
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• pp.95-105
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• 2009

Fuel cells are applied to the propulsion system of aircraft based on environmental-friendly characteristics with low noise and zero emission of CO2, currently many kinds of UAV and small manned aircraft equipped with fuel cells are being developed. Fuel cells for aircraft typically classified into PEMFC(Proton Exchange Membrane Fuel Cell) type and SOFC(Solid Oxide Fuel Cell) type and the system is developed to adapt missions and operational conditions of aircraft. For UAV, various types of aircraft mostly based on PEM fuel cell technology are investigated for military or commercial uses, and the stability and endurance of system will be improved. For small manned aircraft, many researches are carried out to substitute the propulsion system by fuel cell, also some developments for the higher performance of APU of large commercial aircraft to apply fuel cells are in progress. In the future, a fuel cell aircraft will be expected to improve the reliability and efficiency with higher power density.

• Journal of Environmental Policy
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• v.9 no.4
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• pp.77-102
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• 2010

The purpose of this paper is to analyze the Japanese emission trading system and climate change policy thereby contributing to the instituting of similar systems that will be viable for the Korean context. In applying such analyses, it is important to include a careful consideration of cost sharing between stakeholders and firms, an enhancement of the trust worthiness of data concerning greenhouse gases, and an examination of related infrastructure such as emissions authentication agencies and their development. Moreover, it is important to minimize the outflow of domestic resources such as offset credit, green electricity certification system, and ecopoint, making compatible economic growth and carbon reduction thereby encouraging the production and dissemination of 'Environmental Value' as well as connecting 'Environmental Value' to a emission trading system.

• Journal of Environmental Policy
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• v.12 no.3
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• pp.97-122
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• 2013

The ARDL(Autoregressive Distributed Lag) method is employed analyzes the long-run equilibrium relationships among environmental pollution($CO_2$ emissions) per capita, income levels per capita, and energy consumption per capita. The error correction model is employed to analyze the short-term effects of income and energy consumption on $CO_2$ emissions. The Toda-Yammamoto method is employed for causal analysis among the three variables. The results show that income levels, energy consumption, and $CO_2$ emissions are cointegrated. We found the N type relationship between income and $CO_2$ emissions. Long-term elasticities of income and energy consumption with respect to $CO_2$ emission were greater than their short-term elasticities. There were a bilateral causality between energy consumption and $CO_2$ emissions. There was a unilateral causality from $CO_2$ emissions to income and from energy consumption to income not vice versa. Energy consumption can be an important variable to contribute to forecasting $CO_2$ emissions.

• Aerospace Engineering and Technology
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• v.11 no.1
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• pp.98-102
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• 2012

These days, Uncooled IR Systems are more popular in the area of defense and aerospace than before. Uncooled IR Systems are widely used as core technology for making unmanned systems and detecting enemy objects during the day and night in the distance. Recently, researches on TEC-less IRFPA have been increased to minimize the power consumption and to make a smaller system than before. For this, it needs to find adequate NUC(Non-Uniformity Correction) coefficients as FPA(Focal Plane Array) temperature changes. In this paper, we propose a new NUC coefficient estimating technique, DCCE-LI(Dynamic Calibration Coefficients Estimation with Linear Interpolation), for TEC-less IRFPA. It is based on a linear interpolation method and it can estimate NUC coefficients in real-time. So, by testing and evaluating it with some IR images, we conclude that the quality of IR images using proposed method is better than applying static coefficients.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.14-23
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• 2013

Fault management design of the satellite describes preparations for failures which can occur during operational phase. Fault management design contains detection and isolation function of anomaly, and also it contains function to maintain the satellite in safe condition until the ground station finds out a cause of failure and takes a countermeasure. Unlike normal operation, safing operation is automatically performed by Power Control and Distribution Unit and Integrated Bus Management Unit which loads Flight Software without intervention of ground station. Since fault management operation is automatical, fault management logic and functionality of relevant hardware should be thoroughly checked during ground test phase, and error which is similar to actual should be carefully applied without damage. Verification test for fault management design is conducted for various subsystems of satellite. In this paper, we show the design process of fault management design verification test for Electrical Power Subsystem and Attitude and Orbit Control Subsystem of Low Earth Orbit satellite flight model and the test results.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.57-63
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• 2013

The mission of a lot of satellites on geostationary orbit is the communication and/or the broadcasting. These satellites need a big power, so these have a large solar array. Recently, the new satellite for Earth environment monitoring is developing on geostationary orbit. The payload of Earth monitoring satellite requires better thermal condition on detector. Therefore this satellite uses a boom for the attitude stability instead of rejecting one-side solar array as a heat source. The other hand, it uses some momentum wheels being a more momentum capacity to control the large disturbance by solar pressure due to the asymmetric solar array configuration. In this paper, the analysis on the wheel allocation and the wheel off-loading for COMS is summarized and the results are verified by telemetry of COMS. COMS has no boom and a perfectly asymmetric solar array configuration, and it is operating well on geostationary orbit.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.167-167
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• 2011

한국표준과학연구원에서는 국제표준화기구에서 제정한 국제규격(ISO, PNEUROP, DIN, JIS, AVS 등)에 기반을 둔 터보분자펌프의 특성평가시스템을 자체적으로 설계/제작 하였고, 터보분자펌프 1,000 L/s 급의 Database를 구축하였다. 이것을 토대로 특성평가시스템의 신뢰성 확인과 Feedback을 통한 시제품 개발 및 평가지원을 위해 터보분자펌프 2,500L/s 급의 Database를 구축한다. 터보분자펌프의 배기성능을 나타내는 가장 중요한 항목인 배기속도는 분자류 영역에 따라 상이한 가스($N_2$, He)를 사용하여 Throughput method와 Orifice method 두 가지 방법을 병행하여 측정한다. 측정함에 있어서 측정게이지, 유량계 및 Orifice conductance의 불확도에 의하여 배기 속도에 많은 측정오차를 포함하고 있다. 측정 오차를 줄이기 위하여 1% 이상의 안정성과 4%의 오차만을 허용하는 자전 회전자게이지(SRG)와 $10^{-3}$ mbar-L/s 영역까지의 유량 주입범위를 가지는 불확도 ${\pm}$3%의 정적형 유량시스템(CVFM)을 사용하였다. Orifice method의 경우 고진공영역으로 진입할수록 커질 수밖에 없는 배기속도 측정 불확도를 최소화하기 위해 검증된 유량을 이용한 Conductance 값을 제시하여 두 방법에서 얻은 배기속도의 불연속적인 문제를 해결한다. 본 연구에서는 2,500 L/s 급 터보분자펌프는 무거운 기체 $N_2$와 가벼운 기체 He을 사용하여 압축비의 변화와 분자류 영역에 따른 배기속도 변화를 연구하고, 2,500 L/s 급 터보분자펌프의 측정능력을 검증한다. 차후에 배기속도뿐만 아니라 소비전력, 소음, 진동, 온도 등의 특성평가의 전반적인 사항을 평가하여 터보분자펌프 2,500 L/s 급의 database를 완비해간다. 터보분자펌프 특성평가시스템을 사용한 1,000 L/s 급과 2,500 L/s 급 특성 Data를 비교, 분석하여 신뢰성 파악 및 표준화 방안을 개발하고, 고진공펌프 개발 주체와의 feedback 지원 기능의 infra를 구축한다.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.242-250
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• 2004

This paper describes the detection method of wire-like obstacles using millimeter-wave radar system. Passive sensor like CCD camera can be used for the detection of high power electric cables on the hills or mountains and it can give very good quality of obstacle target information. But this system is very limited to use by bad weather condition. The detection capability for different diameters of wire targets using millimeter radar system have been accomplished. To simulate the target on the moving helicopter, rotating targets are used with fixed radar system. In the experiment 11mm, 16mm and 22mm diameter of wires have been detected in single, two and three wires in one position. The detected signal from single wire was very clear on gray level image. Three wires placed very closely together could be recognized in range, cross range image plane. For two and three wires, blur effect due to mutual scattering effect is observed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.58-65
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• 2009

Recently, the Korea Tilting Express(TTX), "HANVIT 200", KRRI(Korea Railroad Research Institute) developed runs for test on the conventional railroad, Honam line, Center line, Chunk-buk line and Tae-baek line. In this paper, we measured the service voltage while TTX ran on the conventional railroad and analyzed the condition of voltage. For measuring voltage directly, we installed PT under the pantograph and measured the voltage of the primary winding. In addition, we record situations that other trains pass by TTX and environments while TTX ran. And then we analyzed the condition of voltage using the records and CBEMA curve. In result, over 110[%] voltage of rated voltage(25[kV]) often occurred and the voltage of some place continued over 110[%] for about 200[s]. Especially, the voltage condition of Tae-baek line is the worst. The results in this paper can help to stabilize the power device and power converter of TTX.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.270-270
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• 2015

소수력은 물이 가지는 위치 에너지나 운동 에너지를 동력으로서 이용하는 것 또는 그렇게 얻을 수 있는 에너지로 소수력발전에 의해 생산되는 에너지는 부존자원이 풍부하여 다른 신재생에너지에 비해 높은 잠재력을 가지고 있어 개발가치가 충분한 부존자원이다. 또한, 친환경적인 청정에너지 중 하나로 대체 에너지원에 비해 높은 에너지를 가지고 있어 개발가치가 큰 부존자원으로 평가되고 있으며, 초기투자비에 비해 유지관리비용이 낮은 편이다. 이러한 개발가치가 있는 잠재 소수력 에너지를 알아보기 위해 한강권역의 표준유역인 안양천을 대상으로 산정해 보았다. 안양천의 잠재 소수력 에너지 산정을 위해 2004년 1월 1일부터 2013년 12월 31일까지의 구로 강우관측소의 일강우자료와 신정수문관측소의 일수위자료 및 유량자료를 수집하였으며, 하상정보를 파악하였다. 낙차는 수차발전기를 회전시켜 전기를 생산하여 상용발전이 가능하며 소수력 발전을 최대치로 생산할 수 있는 조건의 낙차인 2m로 선정하여 소수력 산정공식에 적용하였다. 이에 본 연구에서는 여름인 7월에 1,421.1Kw로 최대값으로 나타났으며, 겨울인 12월에 최소값인 141.9Kw로 나타나 안양천에는 월간 최소 100Kw이상의 전력을 생산할 수 있는 잠재 소수력 에너지를 보유하고 있는 것으로 판단된다. 추후, 국토교통부와의 협력을 통해 관측되는 수문자료(강우, 수위, 유량)를 실시간으로 제공받아 일단위, 월단위, 년단위, 계절단위의 잠재 소수력 에너지를 실시간으로 산정할 수 있는 환경을 구축하여 지속적으로 잠재 소수력 에너지를 평가하고 재생에너지 확보를 통해 추구할 수 있는 경제적 이익 또한 분석되어야 할 것으로 판단된다.