• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.44-46
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• 2001

Increase of gate leakage current causes decrease of gain and increase of noise. In this paper, gate leakage current of GaAs MESEFTs' has been traced with different temperatures from $27^{\circ}C\;to\;350^{\circ}C$ to obtain the zero voltage saturation current $J_s$ which is critical to the temperature dependency of total current. From the results, thermal leakage current coefficient has been proposed to compensate for the total current due to the thermionic emission, tunneling, generation and/or hole injection.

• New & Renewable Energy
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• v.7 no.3
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• pp.59-66
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• 2011

Recently, an UAV using green energy for propulsion has been developed due to exhaustion of fossil fuel. This aircraft runs on electric motors rather than internal combustion engines, with electricity coming from fuel cells, solar cells, ultracapacitors, and/or batteries. Especially solar cells are installed in HALE UAV and flight tests are performed in the stratosphere. Although the solar powered UAV has the advantage of zero emission, its energy conversion efficiency is low and operation time is limited. Therefore, the solar powered UAV has been designed to operate with the secondary battery obtaining flexibility of energy management. In this study, we suggest the new operational concept of the solar powered UAV using directed-energy rayed from the surface of earth to UAV. An UAV is able to secure additional power through attaching solar cell to the lower surface of elevator. As a result, the additional energy supplied by directed-energy can improve the energy management and operational flexibility of the solar powered UAV.

• Journal of Photoscience
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• v.7 no.3
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• pp.97-101
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• 2000

The 77 K emission and excitation spectra, and 298 K infrared and absorption spectra of mer-[CrCl(en)(dpt)]ZnCl$_4$(en=1,2-diaminoethane; dpt=1,5,9-triazanonane) have been measured. Ligand field electronic transitions due to spin-allowed and spin-forbidden are assigned. The zero-phonon line in the excitation spectrum splits into two components by 151$cm^{-1}$ /, and large$^2$E$^{g}$ splitting can be reproduced by the modern ligand field theory. It is confirmed that nitrogen atoms of the en and dpt ligands have a strong $\delta$-donor character, but chloride ligand has weak $\delta$-and $\pi$-donor properties toward chromium(III) ion.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.3
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• pp.109-115
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• 2018

This paper proposes the method to develop the fuel of suljigemi pellet using agricultural by-products the occurred during the manufacturing of alcohol. The goal of the development of suljigemi using biomass is to make the pellet fuel of high calorie. The suljigemi pellet is difficult to recycle waste in the manufacture company of alcohol. suljigemi pellet has the effect of zero emission as the soil conditioner using ash after burning. Also suljigemi pellet has the reduction effect of carriage fee, fuel economy and low-cost high-efficiency effects, environmentally clean fuel as CO2 emissions savings. So the technologies of the suljigemi fuel pellet are developing low carbon, green growth renewable energy fuel through futuristic energy system will be. In experiments, suljigemi pellets confirmed the calories by about 10% higher than wood pellets with the same conditions.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1322-1324
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• 2001

FuelCell/Battery hybrid power systems were studied to develop high efficient zero-emission fuel cell electric vehicles. Fuel cells were used as an auxiliary energy source and batteries were used as a transient power source. The fuel cell system is used to supply the average power demand. Dynamic response of the hybrid systems was simulated using PSPICE program and also tested experimentally. The results can be used to design the interface module and to determine the power requirement between the fuel cell unit and the battery pack.

• Resources Recycling
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• v.10 no.2
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• pp.3-12
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• 2001

Nowadays, countries all over the world are deeply concerned about pollution in the global environment, so they are seeking various ways to adequately disposal of waste. Still, the environmental situation seems to be getting worse and worse. It is evident that such wastes and pollution have been endangering human life nestled in this globe up to the end of the 20th century. We should not, however, tolerate such human misconduct and mal-management of resources any more in the new millenium. For realizing a society that is sustainable for generations to come, it is important to establish a social system for minimizing wastes, promote re-use and recycling, and develop technology for improving recycling efficiencies, including product designs that facil-itate re-use and recycling and innovative technologies for processing wastes. In this paper, reviewing the current status of Korean waste problems, the governmental policy and specific approach for the establishment for recycling society is considered.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.210-211
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• 2014

Nowadays, as to reduce the emission volume of CO₂, blast furnace slag has been widely used to replacement of cement. Techniques about using industrial by-products has been extensively studied. For the previous study, blast furnace slag has been used with recycled fine aggregates. In thess study, considering about the different properties of blast furnace slag, as the change of blaine and chemical performances of blast furnace slag, the results of flowability and compressive strength has been analysed.

• Journal of Photoscience
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• v.7 no.1
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• pp.21-26
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• 2000

The photoemission and excitation spectra of cis-[Cr(cyclam)F$_2$]ClO$_4$ (cyclam = 1,4,8,11-tetraazacy-clotetradecane) taken at 77 K are reported. The 298 K mid- and far-infrared spectra are also measured. The vibrational intervals of the electronic ground state are extracted from the far-infrared and emission spectra. The ten electronic bands due to spin-allowed and spin-forbidden transitions are assigned. The zero-phonon line In the excitation spectrum splits into two components by 169 cm$^{1}$, and the large $^2$E$_{g}$ splitting can be reproduced by the ligand field theory. According to the ligand field analysis, we can confirm that nitrogen atoms of the cyclam ligand have a strong c-donor character, and fluoride ligand also has strong $\sigma$- and $\pi$-donor properties toward chromium(III) ion.n.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.49.2-49.2
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• 2018

Flux calibration for narrow band photometric data gives us an opportunity to get a line flux of extended targets. We developed flux calibration processes for narrow band photometry using broad band filters as a continuum indicator. We derived parameters for color correction and zero point correction including color terms. Applying our method, we successfully subtracted continuum emissions and calibrated the emission lines from an FU Ori type object, V960 Mon.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.960-961
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• 2015

청정지역으로 규정된 제로에미션 지역을 통과하기 위해서는 배터리를 포함한 전기시스템을 사용하여 외력 특성과 무관하게 안정된 운전성능을 유지해야만 한다. 또한 전기시스템이 항구에서 완충된 상태로 출항이 진행되어서 목표지점에 도착한 경우 뿐만 아니라, 운항 중 발전기 시스템에서 배터리를 충전하고 회항지점에서 항구까지 안정된 전력을 유지해야만 한다. 그러나 운항이 진행되면서 선체에 작용되는 외력을 극복하기 위해 추진력을 급속히 변화하게 된다. 이러한 방법은 제한된 에네지를 사용하는 전기시스템에서 급격한 속도 변화는 에너지 사용량을 증가시키고, 진동, 발진등 추진체에 수명을 단축시키는 단점을 가지고 있다. 본 논문에서는 전기시스템의 전력 변화량을 기반으로 제로에미션을 운항하는 운전방법을 제안한다. 제안된 속도제어방법은 모드별로 선정된 속도변화량을 기준으로 모터의 토크응답성과 전력 변화특성을 PSIM을 사용하여 모의시험하였고, 구동부 하드웨어를 구현하여 성능을 부하 모의시험장치에서 검증하였다.