• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.229-233
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• 2012

Proton exchange membrane fuel cell (PEMFC) is the most promising energy source for the robot applications because it has unique advantages such as high energy density, no power drop during operating, and easy to make compact size. However, PEMFC has intrinsic disadvantages which are delay to start up and difficulty to correspond drastic load changes. These disadvantages can be compensated by hybrid operating with a Li-poly battery. This study is focus to build and understand the hybrid system for the robot system. In this study, we build the PEMFC hybrid system using EOS-320 PEMFC stack, Li-poly battery and G-Philos FDX1-250BU dc-dc converter. The hybrid system is accurately monitored by CAN and RS485. The system was studied under two conditions such as non-loaded and loaded operating conditions. The results show that the system has delay to start up without hybrid operating and it can be compensated with the hybrid operating.

• Journal of Astronomy and Space Sciences
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• v.22 no.4
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• pp.537-558
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• 2005

This paper addresses the results of HAUSAT-2 radiation environment and effect analyses, including TID and SEE analyses. Trapped proton and electron, solar proton, galactic cosmic ray models were considered for HAUSAT-2 TID radiation environment analysis. TID was analyzed through total dose-depth curve and the radiation tolerance of TID for HAUSAT-2 components was verified by using DMBP method and sectoring analysis. HAUSAT-2 LET spectrum for heavy ion and proton were also analyzed for SEE investigation. SEE(SEU, SEL) analyses were accomplished for MPC860T2B microprocessor and K6X8008T2B memory. It was estimated that several SEUs may occur without SEL during the HAUSAT-2 mission life(2 years). Software Hamming Code EDAC has been implemented to detect and correct the SEU. In this study, all radiation analyses were conducted by using SPENVIS software.

• Journal of the Korean Solar Energy Society
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• v.32 no.spc3
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• pp.289-294
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• 2012

In recent years, understanding the dynamics of DC distribution system has become critically important due mainly to the increasing needs for the interconnection of DC distributed generators and the (DC-based) electric vehicle (EV) charging systems. In this paper, the characteristics of the DC grid system connected to the compact proton exchange membrane fuel cell (PEMFC) has been studied. In particular, the voltage and current transient phenomena were measured by varying the load of the DC grid system. Also, the voltage and current ripple were measured at the different load conditions. Our experimental results clearly manifested that the study contributes to the establishment of fundamental method to characterize the small DC grid system including distributed generation.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.101.2-101.2
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• 2011

We have developed solar and space weather monitoring system for space weather users since 2007 as a project named 'Construction of Korea Space Weather Prediction Center'. In this presentation we will introduce space weather monitoring system for Geostationary Satellites and Polar Routes. These were developed for satisfying demands of space weather user groups. 'Space Weather Monitoring System for Geostationary Satellites' displays integrated space weather information on geostationary orbit such as magnetopause location, nowcast and forecast of space weather, cosmic ray count rate, number of meteors and x-ray solar flux. This system is developed for space weather customers who are managing satellite systems or using satellite information. In addition, this system provides space weather warning by SMS in which short message is delivered to users' cell phones when space weather parameters reach a critical value. 'Space Weather Monitoring System for Polar Routes' was developed for the commercial airline companies operating polar routes. This provides D-region and polar cap absorption map, aurora and radiation particle distribution, nowcast and forecast of space weather, proton flux, Kp index and so on.

• Journal of the Korean Solar Energy Society
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• v.31 no.2
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• pp.1-7
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• 2011

PEM 연료전지에 있어서 수분의 균형이 연료전지의 시스템 성능에 현저한 영향을 미친다. 그래서 수분 균형은 가장 중요한 요소 중의 일부가 되었으며, 이에 관한 연구가 광범위하게 이루어지고 있다. 적절한 수분 균형을 유지하기 위해서는 적당한 멤브레인 수화작용(membrane hydration)이 필요하며, 반대로 촉매층(catalyst layer)에서의 익수(water flooding)현상이 없어져야 한다. 따라서 이와 같은 동적 상태에서 PEM 연료전지 내의 수분 균형을 유지하기 위해서는, 고도의 동적 수분 조정 기술이 확보되어야 한다. 현재의 연구는 이러한 특성을 고려하여 PEM 연료전지에서 동적부하 상태에서의 수분 이동에 관한 일차원 해석 모델에 관한 것이다. 금번 모델링의 결과, 양극촉매층(CCL, cathode catalystlayer)에서의 수분 상태는 거의 포화 단계에 이르고 있음을 보여주고 있으며, 이 모델링은 연료전지가 작동되는 동안의 CCL에 나타나는 수분의 양상을 예측하는데 활용될 수 있다. 본 논문에서는 수분 이동 모델이 국제규격에 따라 다양한 수송기관이 가동될 때, 동적부하 상태에서 서로 다른 차이점을 발견하기 위한 시뮬레이션 결과에 초점이 맞추어져 있다. 이 모델링을 적용한 결과, 수분 포화도가 상태에 따라 상이하게 나타남을 알 수 있었고, 또한 정적 수분 조절 요소에 따라 최적 상태가 모든 동적 분포에 따라 달라짐을 알 수 있었다.

• Journal of Space Technology and Applications
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• v.3 no.4
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• pp.333-341
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• 2023

This study aims to develop technology for testing and verifying the space radiation environment of miniature space components using the facilities of the domestic 100 MeV proton accelerator and the Space Component Test Facility at the Space Testing Center. As advancements in space development progress, high-performance satellites increasingly rely on densely integrated circuits, particularly in core components components like memory. The application of semiconductor components in essential devices such as solar panels, optical sensors, and opto-electronics is also on the rise. To apply these technologies in space, it is imperative to undergo space environment testing, with the most critical aspect being the evaluation and testing of space components in high-energy radiation environments. Therefore, the Space Testing Center at the Korea testing laboratory has developed a radiation testing device for memory components and conducted radiation impact assessment tests using it. The investigation was carried out using 100 MeV protons at a low flux level achievable at the Gyeongju Proton Accelerator. Through these tests, single event upsets observed in memory semiconductor components were confirmed.

• Journal of Astronomy and Space Sciences
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• v.29 no.4
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• pp.329-336
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• 2012

Korea Astronomy and Space Science Institute researchers have installed and operated magnetometers at Bohyunsan Observatory to measure the Earth's magnetic field variations in South Korea. In 2007, we installed a fluxgate magnetometer (RFP-523C) to measure H, D, and Z components of the geomagnetic field. In addition, in 2009, we installed a Overhauser proton sensor to measure the absolute total magnetic field F and a three-axis magneto-impedance sensor for spectrum analysis. Currently three types of magnetometer data have been accumulated. In this paper, we use the H, D, Z components of fluxgate magnetometer data to investigate the characteristics of mid-latitude geomagnetic field variation. To remove the temporary changes in Earth's geomagnetic filed by space weather, we use the international quiet days' data only. In other words, we performed a superposed epoch analysis using five days per each month during 2008-2011. We find that daily variations of H, D, and Z shows similar tendency compared to previous results using all days. That is, H, D, Z all three components' quiet intervals terminate near the sunrise and shows maximum 2-3 hours after the culmination and the quiet interval start from near the sunset. Seasonal variations show similar dependences to the Sun. As it becomes hot season, the geomagnetic field variation's amplitude becomes large and the quiet interval becomes shortened. It is well-known that these variations are effects of Sq current system in the Earth's atmosphere. We confirm that the typical mid-latitude geomagnetic field variations due to the Sq current system by excluding all possible association with the space weather.

• Advances in materials Research
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• v.6 no.2
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• pp.129-153
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• 2017

Platinum is a transition metal that is very resistant to corrosion. It is used as catalyst for converting methyl alcohol to formaldehyde, as catalytic converter in cars, for hydrocracking of heavy oils, in Fuel Cell devices etc. Moreover, Platinum compounds are important ingredient for cancer chemotherapy drugs. The nano forms of Platinum due to its unique physico-chemical properties that are not found in its bulk counterpart, has been found to be of great importance in electronics, optoelectronics, enzyme immobilization etc. The stability of Platinum nanoparticles has supported its use for the development of efficient and durable proton exchange membrane Fuel Cells. The present review concentrates on the use of Platinum conjugated with various metal or compounds, to fabricate nanocomposites, to enhance the efficiency of Platinum nanoparticles. The recent advances in the synthesis methods of different Platinum-based nanocomposites and their applications in Fuel Cell, sensors, bioimaging, light emitting diode, dye sensitized solar cell, hydrogen generation and in biosystems has also been discussed.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.270-273
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• 2011

Water management is important in proton exchange membrane fuel cell because the water balance has a significant impact on the overall fuel cell system performance. In fuel cell vehicle, the vehicle's power demand is dynamic; therefore, the dynamic water management system is required. This present study proposes a method to control the humidity of the input air in cathode side of the fuel cell vehicle. The simulation using several driving cycles shows the proposed air humidification control obtains a relatively good result. The liquid saturation level is seen constant at the target level although still there are small deviations at driving cycles which having averagely high power demands.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.181.2-181.2
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• 2012

우주공간에서는 solar particle과 galactic cosmic ray에 포함된 proton, electron 및 heavy ion등에 의해 radiation 현상이 발생하는데 이는 각종 전자장비의 성능 감쇄 및 디지털 장비의 내부 정보를 교란을 야기할 수 있다. 특히 메모리의 bit 정보가 반전되는 Single Event Upset (SEU)의 경우 인공위성 및 우주정거장 등의 시스템에서도 빈번히 발생할 수 있으며 적절한 조치가 이루어지지 않으면 주어진 임무 수행 실패는 물론 시스템 failure까지 이를 수 있다. 따라서 SEU에 의한 문제 발생 시 신속한 문제 확인 및 대처가 매우 중요하다. 본 논문에서는 SEU의 발생 원인 및 영향과 기존의 오류 검출 및 수정 기법에 대해 소개하도록 한다. 또한 효율적이고 신뢰성 있는 설계를 위해 각 하드웨어 소자 특성에 따른 적합한 SEU 회피 방안을 제시하도록 한다.